海温分布型对长江中下游旱涝的影响
INFLUENCE OF SST PATTERN ON THE RAINFALL IN THE MIDDLE AND LOWER REACHES OF THE YANGTZE RIVER
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摘要: 采用经验正交函数 (EOF) 分解、奇异值分解 (SVD) 及相关、合成分析等方法, 分析了太平洋海温异常分布与东亚大气环流及长江中下游降水的关系.结果表明:涝、旱年太平洋海温差值场从前一年秋季至当年夏季一直维持由西北向东南“+ - + -”分布特征, 这种太平洋海温分布型与东亚-太平洋遥相关型 (EAP) 密切相关.旱涝年前期太平洋海温异常分布使得低纬度对流活动有明显差异, 而对流活动的异常分布又导致西太平洋副高及东亚大气环流的异常, 从而影响长江中下游降水.数值试验进一步表明:长江中下游旱涝不仅与热带, 同时也与中高纬太平洋的海温异常有关.
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关键词:
- 太平洋海温异常分布型;
- 东亚-太平洋遥相关型;
- 长江中下游降水
Abstract: By using the methods of EOF, SVD, correlation and composite analysis, the relationship between Pacific SSTA pattern and rainfall in the middle and lower reaches of the Yangtze River is investigated. Results suggest that SSTA from northwestern Pacific to southeastern Pacific maintains the pattern of "+ - + -" from the previous autumn to the subsequent summer, bearing a close relation to the EAP. The Pacific SSTA in the previous winter and spring led to the remarkable convection anomalies in low latitudes, which thereby resulted in the anomalous western Pacific Subtropical High and the rainfall in the Yangtze River Basin. Numerical simulations further confirm that rainfall in the middle and lower reaches of the Yangtze River is not only related to the tropical SSTA but also to the SSTA in the mid-latitude Pacific. -
表 1 EAP指数准4年滤波前后与太平洋海温距平EOF分析时间系数的相关
表 2 试验设计
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