| 摘要: |
| 【目的】为探讨大娄山脉地形在贵州遵义强降水过程中的动热力作用。【方法】利用地面加密自动气象站资料、探空资料、多普勒天气雷达资料及ERA5再分析资料等，针对贵州遵义2023年5月20日夜间一次局地强降水过程的降水特征、环流形势、物理量场及中尺度对流系统演变等方面进行分析。【结果】（1）过程发生在200 hPa分流辐散及中低层低槽、低涡切变辐合共同影响下，持续的上升运动配合整层高温高湿是该过程降水时间长、累积雨量大的重要原因。（2）大娄山地形使得850 hPa东南暖湿气流在迎风面聚集，导致θse及相对湿度梯度大值区沿着大娄山脉呈东北-西南向分布，使山脉东侧始终维持高能高湿的大气层结不稳定状态，为强降水的发生提供了有利条件。（3）持续的上升运动及暖湿气流输送使得两个中尺度对流系统合并东移南压，列车效应明显，最终造成大暴雨。（4）源源不断的低层东南气流自大娄山脉北部习水、桐梓之间的“V”型地形南侧翻山而过，由于娄山西支北端及金佛山地形阻挡，形成水汽通量大值中心，并在下风方形成水汽辐合带，产生水汽聚集效应，对流触发于地面辐合线北部与水汽通量散度梯度大值区重叠位置。【结论】该分析得出娄山中小尺度地形对贵州遵义地区降水过程中的动热力条件有重要影响，为揭示娄山地形影响下此类强降水天气过程的成因提供了参考。 |
| 关键词: 大娄山；中小尺度地形；地形作用；假相当位温；中尺度对流系统 |
| DOI： |
| 投稿时间：2024-03-15修订日期：2024-08-22 |
| 基金项目: |
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| Analysis of a heavy rainstorm process in Zunyi, Guizhou under the influence of medium and small scale topography in Loushan |
| LI FENG DAN,LIU HONG SHUANG,XIAO LEI,LIU YUAN MEI,LIN XUE FEI,LUO HAI SHUN |
| (Zunyi Meterological Bureau;Bijie Meterological Bureau;Renhuai Meterological Bureau) |
| Abstract: |
| Based on the data of encrypted automatic weather stations, radiosonde data, Doppler weather radar data and ERA5 reanalysis data, this paper analyzes the precipitation characteristics, circulation situation, physical field and mesoscale convective system evolution of a local heavy precipitation process on the night of May 20, 2023 in Zunyi, Guizhou Province. The dynamic and thermodynamic effects of the medium and small scale landforms in Loushan Mountain during this process are discussed. The results show that: (1) the process occurred under the influence of 200hPa divergence and convergence of low trough and low vortex shear in the middle and lower layers. The continuous upward movement and high temperature and high humidity in the whole layer are the important reasons for the long precipitation time and large cumulative rainfall in the process. (2) The topography of Dalou Mountain makes the 850hPa southeast warm and humid air gather on the windward side, resulting in the θse and relative humidity gradient large value area along the Dalou mountain range in the northeast-southwest distribution, there is a θse and relative humidity large value area on the east side of the mountain range, that is, the unstable state of high energy and high humidity atmospheric junction is always maintained in the heavy rain area, providing favorable conditions for the occurrence of heavy precipitation. (3) The geostrophic deviation of the friction layer makes the 850hPa southerly air flow turn to southeast air flow when it passes over the central mountainous area of Guizhou. When the southeast air flow crosses Dalou Mountain, it forms a lee trough due to the conservation of potential vortex, and finally forms a stable north-south shear in southeast Sichuan. The shear is often triggered by convection near the shear, and under the action of the guiding air, the convection moves eastward and affects the northern area of Zunyi City downstream. (4) The steady flow of low-level southeast air from the north of Dalou mountain range between Xishui and Tongzi "V" shaped terrain across the south side of the mountain, due to the north end of the west branch of Loushan Mountain and the topography of Jinfou Mountain, formed a maximum value center of water vapor flux, and formed a water vapor convergence zone downwind, resulting in water vapor accumulation effect. Convection is triggered at the overlapping position between the northern part of the surface convergence line and the large value area of the divergence gradient of water vapor flux. |
| Key words: Dalou Mountain; Small and medium scale topography; Topographic effect; Pseudoequivalent potential temperature; Mesoscale convective system |
