四川省夏季夜雨的空间变化特征

Spatial 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，本文利用了四川省1961~2021年共61年全省126个基本气象站的逐日降水观测资料，采用旋转经验正交函数分解(Rotated Empirical Orthogonal Function decomposition，以下简称REOF分解)，详细探讨了四川省夏季夜雨降水的空间变化特征。结果表明：1) 四川省夏季夜雨空间分布是非常不均匀的，总体上呈现出南部多，北部少的分布形式；盆地与高原交界的山区明显偏多，盆地和高原内部相对偏少的分布特征，其中在雅安天全县到乐山市区一带，夜雨呈现出显著的最大值，普遍超过500 mm甚至局地达到了700 mm。四川盆地夏季夜雨日数相对较低但是夜雨强度更大，而川西高原地区夏季夜雨日数相对较高但是夜雨强度较小。2) REOF分析结果表明四川省夏季夜可划分为四个区域，分别为：盆地西北型(方差贡献率为25.7%)、川东北型(方差贡献率为17.3%)、南北相反型(方差贡献率为13.6%)和高原盆地相反型(方差贡献率为8.5%)。其中，盆地西北型的增长速度是−0.067·(10a)⁻¹，川东北型的增长速度是−0.087·(10a)⁻¹，南北相反型的增长速度是−0.117·(10a)⁻¹，高原盆地相反型的增长速度是0.074·(10a)⁻¹。

Abstract: In order 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 Sichuan Province from 1961 to 2021 were used. The Rotating Empirical Orthogonal Function decomposition (REOF decomposition) was employed to explore in detail the spatiotemporal variation characteristics of summer night rain precipitation in Sichuan Province. The results show that: 1) The spatial distribution of summer night rain in Sichuan Province is very uneven, generally showing a distribution pattern of more in the south and less in the north; The mountainous areas at the junction of basins and plateaus are significantly more abundant, while the distribution characteristics within basins and plateaus are relatively less. In the area from Tianquan County in Ya’an to Leshan City, night rain shows a significant maximum value, generally exceeding 500 mm or even locally reaching 700 mm. The number of night rain days in summer in the Sichuan Basin is relatively low, but the intensity of night rain is greater, while the number of night rain days in summer in the western Sichuan Plateau is relatively high, but the intensity of night rain is smaller. 2) The REOF analysis results indicate that summer nights in Sichuan Province can be divided into four regions, namely: Northwest Basin Type (variance contribution rate of 25.7%), Northeast Sichuan Type (variance contribution rate of 17.3%), North South Opposite Type (variance contribution rate of 13.6%), and Plateau Basin Opposite Type (variance contribution rate of 8.5%). Among them, the growth rate of the northwest basin type is −0.067·(10a)⁻¹, the growth rate of the northeast Sichuan type is −0.087·(10a)⁻¹, the growth rate of the north-south opposite type is −0.117·(10a)⁻¹, and the growth rate of the plateau basin opposite type is 0.074·(10a)⁻¹.