| 华南一次暴雨过程热力和动力特征的诊断分析 |
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| 引用本文： | 林晓霞,冯业荣,张诚忠,林文实.华南一次暴雨过程热力和动力特征的诊断分析[J].热带气象学报,2017,33(6):975-984. |
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| 作者姓名： | 林晓霞 冯业荣 张诚忠 林文实 |
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| 作者单位： | 1.中国气象局广州热带海洋气象研究所/广东省区域数值天气预报重点实验室，广东 广州 510640 |
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| 基金项目： | 广州市科技计划项目201604020012广东省科技计划项目2017B030314140国家自然科学基金41675099国家自然科学基金41705089 |
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| 摘 要： | 2015年5月19—20日广东省强降水过程具有降水集中、强度大和局地性强的特点，利用广东省自动气象站观测资料、ECMWF_FINE再分析资料，对此次强降水过程进行分析发现:华南地区受低槽东移影响，强降水发生在切变线南侧偏南暖湿流场中，粤北降水属于锋面降水，粤东降水属于锋前暖区降水，两者在水汽输送和动力机制上有显著区别。孟加拉湾和南海输送的水汽在这次强降水过程中占主导地位，南边界和东边界为水汽的流入边界，整体水汽输送以经向输入为主。暖区降水区域处于较强的水汽平流环境中，具有更大的水汽净输送量，造成粤东地区的降水量更大。对流层高层辐散比中低层辐合更为重要，是粤东暖区降水重要的动力属性，且暖区中低层流场的旋转效应弱，有区别于典型的梅雨锋降水。利用绝热无摩擦湿位涡守恒进行诊断发现对流不稳定是此次强降水发展的主要机制，暴雨发生区域对应湿位涡垂直分量为负值，水平分量为正值，底层MPV1＜0和MPV2＞0综合反映了大气对流不稳定和斜压不稳定的增强过程。降水区对流层低层受负湿位涡控制，低层湿位涡负值区与强降水落区有较好的对应关系。
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| 关 键 词： | 华南暴雨 水汽通量 湿位涡 对流不稳定 |
| 收稿时间： | 2016-07-28 |
DIAGNOSTIC ANALYSIS OF THERMAL AND DYNAMIC CHARACTERISTICS OF A RAINSTORM PROCESS IN SOUTHERN CHINA |
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| Affiliation: | 1.Guangzhou Institute of Tropical Marine and Meteorology/Guangdong Province Key Laboratory of Reginal Numerical Weather Prediction, CMA, Guangzhou 510640, China2.Department of Atmospheric Science, Chengdu University of Information Technology, Chengdu 610225, China3.Department of Atmospheric Science, Sun Yat-sen University, Guangzhou 510275, China4.Guangdong Meteorological Observation Data Center, Guangzhou 510640, China |
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| Abstract: | Automatic weather observation data in Guangdong province and ECMWF_FINE reanalysis data are used to analyze a heavy rainfall in the south of China during 19—20 May 2015 with the focus on thermal and dynamic characteristics. The results show that the south of China was affected by an eastward-moving trough and heavy rainfall occurred on the south of a wind shear with a southerly warm airflow. The north rain-band(over the north part of theprovince)resulted from the front system, while the south rain-band(in the northwest part of the province)was in the warm sector of a front. There are significant differences about moisture transportation and power mechanism between the frontal and warm-sector heavy rain. Water vapor from Bay of Bengal and South China Sea played a dominant role in the rainstorm. During the process, the water vapor came in mostly from the southern and eastern boundaries and the whole water vapor transport based mostly on meridional transport. Frontal warm-sector had stronger moisture transport because of the stronger moisture-advection in the front area of strong moisture advection environment. As a result, precipitation over eastern Guangdong became greater. Divergence in upper-troposphere was more important than convergence in low-level, which is the significant dynamic property of precipitation in warm region. Besides, warm region has weaker rotation effects, distinct from the typical Meiyu precipitation. Analysis of the heavy rainfall process in terms of moisture potential velocity(MPV) principle shows that convective instability was the important mechanism for the development of heavy rainfall. The increase in vertical wind shear and moisture barocilinty around the low-level hasa great influence on the development of the vortex. Lower troposphere of rainfall area is controlled by the negative MPV, and the zone with large value of negative MPV has good correspondence with the location of heavy rain. |
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