| 华南地区7-10月两类区域性极端降水事件特征及环流异常对比 |
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| 引用本文： | 孙婧超,管兆勇,李明刚,于亚鑫.华南地区7-10月两类区域性极端降水事件特征及环流异常对比[J].气象学报,2019,77(1):43-57. |
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| 作者姓名： | 孙婧超 管兆勇 李明刚 于亚鑫 |
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| 作者单位： | 1.南京信息工程大学气象灾害教育部重点实验室/气候与气象灾害协同创新中心, 南京, 210044 |
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| 基金项目： | 公益性行业（气象）科研专项（GYHY201406024）、灾害天气国家重点实验室课题（2015LASW-A03）、江苏省优势学科建设项目（PAPAD）。 |
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| 摘 要： | 利用1981—2016年7—10月中国753站逐日降水资料、气象信息综合分析处理系统（MICAPS）逐日站点降水资料、日本东京台风中心西北太平洋热带气旋（TC）最佳路径资料和NCEP/NCAR再分析资料集，分析了华南地区区域性日降水极端事件（RDPE事件）的统计特征及环流异常。根据华南地区RDPE事件的发生是否受热带气旋影响将其分为TCfree-RDPE和TCaff-RDPE两类事件，其中TCaff-RDPE事件占42%且集中发生在8月4—5候；TCfree-RDPE事件以7月发生频数最多，占其总频次的1/2以上。TCfree-RDPE事件发生时，华南地区受异常气旋性环流控制，来自西太平洋和中国南海的暖湿气流与北方冷气团在此汇合并形成一条狭长的水汽辐合带，低层辐合、高层辐散，显著强烈的上升运动为TCfree-RDPE事件的发生与维持提供了有利条件；与此同时，波扰动能量由高原东北侧及河西走廊地区向华南一带传播并在华南显著辐合，有利于华南上空扰动的发展和维持。TCaff-RDPE事件发生时，华南上空由低层到高层的斜压环流结构更为明显，异常上升运动更加强烈，热带气旋在其运动过程中携带了大量源自孟加拉湾、中国南海和西太平洋地区的水汽并输送至华南地区，水汽辐合气流更为强盛。同时，波扰动能量由高纬度地区沿河西走廊向下游传播，但在华南地区辐合不甚明显。两类极端事件发生时，加热场上的差异亦明显。华南及邻近地区上空的大气净加热及其南侧大范围区域的净冷却所形成的加热场梯度对TCfree-RDPE事件的发生有利。而TCaff-RDPE事件发生时，〈Q1〉和〈Q2〉在经向上由18°N以南、华南及其邻近地区、32°N以北呈负—正—负的异常分布型，正距平值更高，加热场梯度更大，有利于TCaff-RDPE事件的维持。这些结果有利于人们认识和预测华南区域性日降水极端事件的发生。
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| 关 键 词： | 华南地区 区域性日降水极端事件 环流异常 热带气旋 |
| 收稿时间： | 2017/12/25 0:00:00 |
| 修稿时间： | 2018/5/13 0:00:00 |
Anomalous circulation patterns in association with two types of regional daily precipitation extremes over South China from July to October |
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| SUN Jingchao,GUAN Zhaoyong,LI Minggang and YU Yaxin.Anomalous circulation patterns in association with two types of regional daily precipitation extremes over South China from July to October[J].Acta Meteorologica Sinica,2019,77(1):43-57. |
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| Authors: | SUN Jingchao GUAN Zhaoyong LI Minggang and YU Yaxin |
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| Institution: | 1.Key Laboratory of Ministry of Education for Meteorological Disaster/Climate and Weather Disasters Collaborative Innovation Center, Nanjing University of Information Science and Technology, Nanjing 210044, China2.State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081, China3.School of Atmospheric Sciences, Chengdu University of Information Technology, Chengdu 610225, China |
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| Abstract: | Using daily precipitation data collected at 753 stations in China and from the Meteorological Information Comprehensive Analysis and Process System (MICAPS), the Southwest Pacific Ocean Tropical Cyclone (TC) optimal path data from the Tokyo Typhoon Center in Japan, and the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis, the statistical characteristics of regional mean daily precipitation extreme (RDPE) events and circulation anomalies in South China were studied. Depending on whether the occurrence of a given RDPE event is affected by TC, the RDPEs are classified into two categories, i.e., TCfree-RDPE and TCaff-RDPE events. The TCaff-RDPE events account for about 42% of the total RDPEs and mainly occur in late August, while the TCfree-RDPE events frequently occur in July. When TCfree-RDPE events occur, South China is controlled by abnormal cyclonic circulations, and the warm and moist airflow from the western Pacific region and the South China Sea merge with the cold air from the north in this region, inducing a long narrow zone of water vapor convergence and significant and strong ascending motion, which are responsible for the occurrence and maintenance of TCfree-RDPE events. Simultaneously, the wave energy propagates from the northeastern side of the Tibetan Plateau and the Hexi Corridor region to South China and converges in this area, which favors the development and maintenance of perturbation over South China. When TCaff-RDPE events occur, the southern part of China is dominated by TC-related strong anomalous cyclonic circulations. The warm, moist air mass is transported into this area from the Bay of Bengal, the western Pacific and the South China Sea, leading to large amounts of latent heat release and strong ascending motion over South China. These results are helpful for better understanding and predicting the occurrence of regional extreme precipitation events in South China. |
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| Keywords: | South China Regional mean daily precipitation extremes (RDPE) Circulation pattern Tropical cyclones |
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