| 中国东部夏季极端降水时空分布及环流背景 |
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| 引用本文： | 方浩,乔云亭. 中国东部夏季极端降水时空分布及环流背景[J]. 热带气象学报, 2019, 35(4): 517-527. DOI: 10.16032/j.issn.1004-4965.2019.047 |
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| 作者姓名： | 方浩 乔云亭 |
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| 作者单位： | 1.中山大学大气科学学院/季风与环境研究中心/广东省气候变化与自然灾害研究重点实验室，广东 广州 510275 |
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| 基金项目： | 国家重点研发计划2016YFA0600601国家自然科学基金项目41575069 |
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| 摘 要： | 基于中国测站的降水资料和NCEP/NCAR逐日再分析资料，取第95百分位数作为极端降水阈值，通过经验正交函数分解(EOF)方法将中国东部分为华南、长江中下游、华北和东北三个地区，定义极端降水事件，并对中国东部夏季极端降水时空分布及环流背景进行研究。结果表明，极端降水事件随日期的变化与中国东部夏季雨带的南北移动相吻合。近54年来，华南极端降水事件频数在1991年左右突增，长江中下游地区有两次突变，1991年左右突增，2000年左右突减。华北和东北地区在1999年左右突减。发生极端降水事件时，低层850 hPa出现局地异常气旋环流，位势高度异常降低，对应低空异常辐合；中层500 hPa，西太副高位置异常偏南有利于华南极端降水的发生，副高西伸有利于长江中下游的极端降水，位置偏北易造成华北和东北极端降水；高层200 hPa，发生极端事件时降水关键区位于西风急流轴右侧，对应异常反气旋环流，这种高层辐散低层辐合的环流配置为极端降水提供动力条件。极端降水的气候平均态水汽主要来源于南半球和西北太平洋。副高的位置异常影响我国东部水汽输送异常，造成不同地区的极端降水。
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| 关 键 词： | 气候学 极端降水 中国东部 环流特征 时空分布 |
| 收稿时间： | 2018-08-02 |
TEMPORAL AND SPATIAL DISTRIBUTION OF SUMMER EXTREME PRECIPITATION AND CIRCULATION BACKGROUND OVER EASTERN CHINA |
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| FANG Hao and QIAO Yun-ting. TEMPORAL AND SPATIAL DISTRIBUTION OF SUMMER EXTREME PRECIPITATION AND CIRCULATION BACKGROUND OVER EASTERN CHINA[J]. Journal of Tropical Meteorology, 2019, 35(4): 517-527. DOI: 10.16032/j.issn.1004-4965.2019.047 |
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| Authors: | FANG Hao and QIAO Yun-ting |
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| Affiliation: | 1.School of Atmospheric Sciences, and Center for Monsoon and Environment Research, and Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies, Sun Yat-sen University, Guangzhou 510275, China2.Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519082, China |
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| Abstract: | Based on the observed daily precipitation data of 756 stations in China and the NCEP/NCAR reanalysis datasets, the 95th percentile was taken as the extreme precipitation threshold. Eastern China was divided into three regions:South China (SC), the middle and lower reaches of the Yangtze River (MLYR), North and Northeast China (NNC) by the Empirical Orthogonal Function (EOF) analysis. After defining extreme precipitation events (EPEs), this paper researches the temporal and spatial distribution of summer extreme precipitation and background over Eastern China. The results show that the variation of EPEs with the date coincides with the north-south movement of the summer rain belt in eastern China. In the past 54 years, the frequency of EPEs in SC experienced an abrupt increase around 1991. There were two abrupt changes in MLYR, one around 1991 and the other around 2000. In NNC, the frequency was reduced around 1999. In the EPEs over each key region, at 850 hPa, an anomalous local cyclonic circulation occurs and the geopotential height anomaly is negative, corresponding to the convergent anomaly. At 500 hPa, the southward advancement of the western Pacific subtropical high (WPSH) is conducive to the occurrence of extreme precipitation in SC. It favors extreme rain in MLYR when the WPSH extends westward. The northward movement of the WPSH is likely to cause extreme precipitation in NNC. At 200 hPa, when the EPEs occur, the key areas of extreme precipitation are located on the right side of the westerly jet axes, with anomalous anticyclonic circulations. This configuration of high-level divergence and low-level convergence provides dynamic condition for extreme rainfall. The climatological water vapor of extreme rain mainly comes from the Southern Hemisphere and the northwestern Pacific. The anomalous position of the WPSH affects the water vapor transport anomaly over eastern China, causing extreme rainfall in different regions. |
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| Keywords: | climatology extreme precipitation eastern China atmospheric circulation spatial and temporal distribution |
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