| 8月柳州一次副高影响下的持续性大暴雨过程分析 |
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| 引用本文： | 李亚琴,蓝柳茹,苏小玲,赖锡柳.8月柳州一次副高影响下的持续性大暴雨过程分析[J].高原山地气象研究,2021,41(4):61-69. |
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| 作者姓名： | 李亚琴 蓝柳茹 苏小玲 赖锡柳 |
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| 作者单位： | 广西壮族自治区柳州市气象局，柳州 545001 |
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| 基金项目： | 柳州市气象局自立项目（柳气科202001）；柳州市科技计划项目（2020NBCA0801）；广西自然科学基金项目（2020GXNSFBA297129） |
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| 摘 要： | 利用常规观测资料、区域自动站雨量资料、NCEP 1°×1°再分析资料以及国家气候中心的副高指数资料，分析2017年8月9~15日柳州北部的持续性大暴雨到特大暴雨天气过程。结果表明:这次连续降雨过程可分为副高稳定且高原小波动东移、副高西进且切变线北抬、华北槽南压且副高东退三个阶段。第一阶段，波动引导干冷空气侵入，低层暖湿空气加大，θse锋区增强，边界层辐合抬升触发暴雨，低层风速辐合为增强机制；强降水发生在锋区南侧西南气流加强过程中，落区稳定，集中在柳州北三县，局地性强，傍晚加强，白天减弱，与高原波动频率一致。第二阶段，副高加强西伸，广西整层转为西南急流，桂北处于急流轴附近，垂直运动存在高低两个中心；桂北处于高温高湿的不稳定层结中，中层受副高下沉气流影响，低层暖湿不稳定能量集聚，当近地层超低空急流加强，急流轴北推时，其左侧的气旋性切变和风速辐合抬升触发暴雨，不稳定能量释放过程中使得高低层两个垂直运动中心打通，上升运动进一步加强；其强降雨落区南界北收到三江融水交界，雨强更大，暴雨成片，无时间间歇。第三阶段，前期副高控制让桂北集聚了大量的暖湿不稳定能量，随着华北槽的东移，中高层干冷空气叠加在高温高湿的不稳定气流之上，随低层切变线南压进入广西，低层强烈的辐合抬升触发强降雨，中高层干侵入对降雨有增强作用，强降雨落区随着副高东退从桂北逐渐南压到桂南，其强度、范围和累计雨量均为最大。
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| 关 键 词： | 暴雨 副热带高压 动力机制 水汽输送 |
| 收稿时间： | 2021-03-26 |
Analysis on the Continuous Rainstorm Process under the Interaction of a Subtropical High Pressure in Liuzhou in August |
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| Institution: | Liuzhou Meteorological Bureau, Liuzhou 545001, China |
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| Abstract: | Using regular observation data and regional automatic station rainfall data, 1°×1° NCEP 6h interval reanalysis data, sub-high index data provided by the National Climate Center, the process of continuous heavy rainstorm to severe rainstorm in northern Liuzhou from 9 to 15 August 2017 was analyzed. The results show that the continuous rainfall process can be divided into three stages: stable subtropical high and eastward movement of small plateau fluctuations, westward movement of subtropical high and northward movement of shear line, southward pressure of North China trough and eastward retreat of subtropical high.In the first stage, the middle layer dry cold air invades, the lower layer warm and wet air increases, and the layer-trough gradient increases. Heavy precipitation occurred on the south side of the front zone. During the process of strengthening the low southwest airflow, the precipitation zone was concentrated in three northern counties of Liuzhou. In the second stage, the subtropical high strengthens and extends westward, and the whole layer of Guangxi turns to the southwest jet stream. North Guangxi is near the jet axis, and there are two centers of vertical motion. Northern Guangxi is in the unstable stratificaiton of high temperature and high humidity. The middle layer is affected by the sub-high subsidence airflow, and the low-level warm and humid unstable energy is concentrated. When the near-surface ultra-low level jet is strengthened and the jet axis is pushed northward, the cyclone shear on the left side and the convergence and uplift of wind speed trigger rainstorm. In the process of unstable energy release, two vertical motion centers in the high and low layers are opened, and the upward movement is further strenghened. The southern boundary of the heavy rainfall area recieved the junction of Sanjiang area, the rain is stronger, the rainstorm is no time interval. In the third stage, the dry cold air in the middle and upper layers expands to the lower layers, where it converges with the warm and wet air in the lower layers. The southern pressure of the lower shear line enters Guangxi. The strong convergence and uplift of the low level triggers heavy rainfall. The dry intrusion of the middle and high levels has an enhanced effect on rainfall. The heavy rainfall area gradually southwards from northern Guangxi to southern Guangxi with the eastward retreat of the subtropical high, and its intensity, range and cumulative rainfall are the largest. strong convergence and uplift of the low level triggers heavy rainfall. The dry intrusion of the middle and high levels has an enhance effect on rainfall. The heavy rainfall area gradually southwards from northern Guangxi to southern Guangxi with the eastward retreat of the subtropical high, and its intensity, range and cumulative rainfall oare largest. |
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