GUO Zhaohua,CHEN Yun,XIAO Tiangui,et al.Analysis of a Double Rain Belts Precipitation Process in the Pre-flood Season of South China[J].Journal of Chengdu University of Information Technology,2025,40(02):170-178.[doi:10.16836/j.cnki.jcuit.2025.02.008]
华南前汛期一次双雨带降水过程分析研究
- Title:
- Analysis of a Double Rain Belts Precipitation Process in the Pre-flood Season of South China
- 文章编号:
- 2096-1618(2025)02-0170-09
- Keywords:
- double rain belts in South China; front; cyclonic shear; moisture potential vorticity; convection triggering
- 分类号:
- P458.1+21.1
- 文献标志码:
- A
- 摘要:
- 为加深华南前汛期双雨带形成机理的科学认识,利用国家级和区域自动站逐小时观测资料、阳江和清远探空资料、多普勒天气雷达组网产品、广州双偏振天气雷达基数据及ERA5再分析资料,采用湿位涡诊断等方法,分析2022年5月华南一次双雨带过程的环境条件及形成机制。结果表明:(1)两条雨带均发生在高湿与层结不稳定的中尺度对流环境中,但北雨带为低涡切变线和锋面等天气系统协同强迫形成的大尺度锋面雨带,强降水落区集中,具有一定的对流性质; 南雨带在弱天气尺度强迫背景下产生,对流性质更强,具有极端性。(2)对流不稳定是北雨带发展的重要机制,低层MPV1<0且MPV2>0对应强降水落区,较强的大气斜压性有利于低涡发展。(3)南雨带夜间东南暖湿气流增强,海陆边界和地形抬升促使气流发生侧向摩擦,触发阳江的初始对流,中等偏弱的深层垂直风切变和γ中尺度涡旋有助于对流组织化; 台山-中山在地面气旋式切变和地形抬升下触发初始对流,配合较弱的冷池出流和温度梯度,有助于对流系统的维持。(4)与北雨带相关的水汽输送来源于700 hPa附近,南雨带的水汽输送来源于850～925 hPa。双雨带之间的弱雨区可能与低空西南急流的位置、中层下沉气流以及低层辐散等因素有关。
- Abstract:
- In order to deepen the scientific understanding of the formation mechanism of double rain belts in the pre-flood season of South China, this paper uses the hourly observation data of national and regional automatic stations, sounding data of Yangjiang and Qingyuan, doppler weather radar network products, Guangzhou dual-polarization weather radar data and ERA5 reanalysis data, by method of moisture potential vorticity diagnosis to analyze the environmental conditions and formation mechanism of a double rain belts event in South China in May 2022. The results are as follows.(1)Double rain belts occurred in a mesoscale convective environment with high humidity and unstable stratification. However, the northern rain belt was a large-scale frontal rain belt formed by the synergistic forcing of low vortex, shear line, front and other weather systems. The precipitation area was concentrated and had certain convective properties. The southern rain belt was generated under the background of weak weather scale forcing. The sudden and nocturnal precipitation was obvious, and the convection was stronger and extreme.(2)Convective instability was the important mechanism for development of the northern rain belt. The area of low-level MPV1<0 and MPV2>0 corresponded to the heavy rainfall area in the northern rain belt. Strong atmospheric baroclinicity was conducive to the development of low-level vortex.(3)The warm and humid southeasterly air strengthened at night in the southern rain belt, and the blocking and uplifting of the land-sea boundary and coastal topography promoted the lateral friction of airflow, triggering the initial convection in Yangjiang. Moderately weak deep vertical wind shear and γ mesoscale vortex contributed to the maintenance of convective organization. The initial convection triggered under the action of surface cyclonic shear and topographic uplift between Taishan and Zhongshan, which was conducive to the maintenance of convective system and precipitation with weak cold pool outflow and temperature gradient.(4)The water vapor transport associated with the northern rain belt came from the vicinity of 700 hPa, and the water vapor transport in the southern rain belt came from 850-925 hPa.The weak precipitation area between the double rain belts may be related to the location of the low-level southwest jet, the middle-level downdraft and the low-level divergence.
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备注/Memo
收稿日期:2023-10-10
基金项目:国家自然科学基金资助项目(42475015、41975001、52239006)
通信作者:谌芸.E-mail:chenyun@cma.gov.cn