XU Yizhou,LI Guoping,ZHANG Xiaoyu,et al.Diagnostic Analysis of Mesoscale Convective System in Southern Jiangsu under the Influence of Typhoon“In-fa”(No.2106)[J].Journal of Chengdu University of Information Technology,2025,40(03):329-338.[doi:10.16836/j.cnki.jcuit.2025.03.013]
2106号台风“烟花”影响下苏南地区中尺度对流系统的诊断分析
- Title:
- Diagnostic Analysis of Mesoscale Convective System in Southern Jiangsu under the Influence of Typhoon“In-fa”(No.2106)
- 文章编号:
- 2096-1618(2025)03-0329-10
- Keywords:
- typhoon periphery; mesoscale convective system; diagnostic analysis; helicity; moist potential vorticity
- 分类号:
- P458.2
- 文献标志码:
- A
- 摘要:
- 为揭示登陆台风外围中尺度对流系统的发展机制和结构特征,利用ERA5再分析资料、雷达、卫星、自动站等多源监测数据对2021年7月28日午后发生在台风“烟花”外围环流内苏南一次强对流过程的环流背景、物理量特征进行分析。研究得出:中尺度对流系统在“烟花”外围偏西北气流下发展,于苏西南形成地面辐合线。发展全过程均呈低层辐合,高层辐散,强盛阶段上升运动达200 hPa。絮状回波合并与强对流始发相关联,云团膨胀机制与强对流迅速发展对应,带状回波纵向加强对应中尺度对流云团点状膨胀。稳定度指数对本次过程有较好前兆指示。降水发生前,z-螺旋度与湿z-螺旋度负值中心已出现于MCS始发区,降水与负螺旋度对应,负值中心位于降水中心西北,湿z-螺旋度较z-螺旋度更能反映MCS消亡阶段特征,螺旋度中心位于800～900 hPa。系统始发区湿正压项呈负值,强盛阶段湿位涡正压项MPV1负值中心与降水中心重合。湿位涡斜压项MPV2随系统发展正值逐渐增强,降水发生在MPV2正值中心和正负MPV2交界处。近地面负MPV1与正MPV2的配置,对MCS降水产生与加强有较好指示。
- Abstract:
- To investigate the development mechanism and structural characteristics of the mesoscale convective system outside the landing typhoon, a comprehensive analysis was conducted using multiple data sources, including ERA5 reanalysis data, radar, satellite, and automatic stations. The focus was on examining the circulation background and physical features of a strong convective event that occurred in southern Jiangsu on July 28, 2021, during the outer circulation of Typhoon “In-fa”. The findings reveal that the MCS developed under northwest airflow outside the typhoon’s influence, resulting in the formation of a surface convergence line in southwest Jiangsu. Throughout its development, this system exhibited lower-level convergence and higher-level divergence. The intense upward motion extended up to 200 hPa. The combination of flocculent echoes is associated with the initiation of MCS, and cloud mass expansion corresponds to rapid convection development. Additionally, The longitudinal intensification of the band radar echo corresponds to the point expansion of the mesoscale convective cloud cluster. The stability index serves as an effective precursor for this process. Prior to precipitation occurrence, the negative centers of z-helicity and wet z-helicity appeared in the initiation area of MCS, which coincided with subsequent precipitation centers located northwestwardly from them. Wet z-helicity better reflects characteristics during the MCS extinction stage compared to z-helicity. Helicity centers are situated between 800-900 hPa.Before precipitation, MPV1 in the initial region of MCS was negative, and the negative MPV1 center coincided with the precipitation center during the system’s robust phase. The MPV2 incrementally increases alongside the development of MCS, resulting in precipitation at the positive MPV2 center and the conjunction of positive and negative MPV2. The configuration of negative MPV1 and positive MPV2 near the ground provides a promising indication for the generation and intensification of MCS precipitation.
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备注/Memo
收稿日期:2023-10-23
基金项目:国家自然科学基金资助项目(42175002); 四川省中央引导地方科技发展资助项目(2024ZYD0175)
通信作者:李国平.E-mail:liguoping@cuit.edu.cn