摘要: |
【目的】探讨新型探测资料在短时强降水天气监测预警中的应用。【方法】利用常规气象观测资料、ERA5再分析资料、风廓线雷达、地基微波辐射计以及雨滴谱资料对贵阳地区2023年3月16日一次短时强降水天气过程进行分析。【结果】(1)短时强降水发生前2 h,垂直运动较弱,垂直风切变强中心向下传播,降水前约 0.5 h,0~7 km垂直速度明显增大,低层上升运动更为显著,正垂直风切变明显增强,低空急流指数迅速增大;(2)19—21时,大气液态水含量呈波动增长,受干侵入影响,1 km以下相对湿度减小,0~8 km形成相对湿度为“上下干中间湿”3 层结构,降水前约 0.5 h,大气液态水含量迅速增大,变为“上干下湿”2 层结构,强降水发生时处于大气液态水总含量波峰;(3)强对流过程处于高能环境,K指数从午后开始超过35 ℃,在降水发生前约 0.5 h,K指数和CAPE均有较大跃升,降水发生时,强烈的西南风低空急流带来了暖湿空气,在0.2~1 km出现逆温,有大于25 ℃的极值中心。(4)本次短时强降水过程雨滴直径与下落速度的关系符合理论关系,降水强度贡献最多的为中等大小粒径的粒子,降水时段,雨滴尺度谱存在明显的双峰结构。【结论】新型探测资料可以更细微的捕捉到短时强降水天气发生前中小尺度特征;垂直速度、低空急流指数和大气液态水含量的显著增大,预示着降水即将开始,急流指数的脉动与雨强之间有很好的对应关系;此外,0~1 km垂直风切变的增大,对强降水的出现有较好的预示作用。 |
关键词: 贵阳;风廓线雷达;微波辐射计;雨滴谱;短时强降水 |
DOI: |
投稿时间:2023-08-29修订日期:2024-02-04 |
基金项目: |
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Analytical Application of Three Kinds of New Observation Data in a Spring Short-time Severe Precipitation Process in Guiyang |
Li Yanlin |
(Guizhou Meteorological Observatory) |
Abstract: |
Based on the conventional meteorological data, ERA5 reanalysis data, and the wind profile radar, ground-based microwave radiometer and disdrometer observation data in Guiyang region, this article analyzes a short-time severe precipitation process that occurred on March 16, 2023, and discusses the application of new detection data in the monitoring and early warning of short-time heavy precipitation. The results show that: (1) In 2 h earlier than the occurrence of short-term heavy rainfall, the vertical motion was weak, and strength center of the vertical wind shear propagated downward. In about 0.5 h ahead of the precipitation, the vertical velocity of 0-7 km increased significantly, the vertical motion of lower layer was more remarkable, the positive vertical wind shear strengthened significantly, and the low-level jet index increased rapidly. (2) From 19:00 to 21:00, the atmospheric liquid water content was increasing by fluctuation. Under the influence of dry air intrusion, the relative humidity below 1 km decreased, thus the atmosphere in the height range of 0-8 km formed a three-layer structure of "dry in the upper and lower layers but wet in the mid layer". In about 0.5 h before precipitation, the content of atmospheric liquid water increased rapidly so that the three-layer structure changed into a two-layer structure of "dry at the top and wet at the bottom". The severe precipitation occurred when the content of atmospheric liquid water peaked. (3) The convection process was in a high-energy environment. The K index began to exceed 35℃ in the afternoon, and in 0.5 h ahead of the precipitation, both the K index and CAPE had a large jump. At the time of precipitation, the low-level jet of strong southwest wind brought warm and moist air, forming a temperature inversion layer at the height of 0.2-1 km with a significantly maximum temperature center higher than 25 ℃. (4) The relationship between raindrop diameter and falling velocity in this short-time heavy precipitation process was in line with the theoretical relationship, and the medium-sized particles contributed most for the precipitation intensity. During the precipitation period, the raindrop size distribution had an obvious bimodal structure. The above results show that the new observation data can meticulously capture the small and medium scale characteristics before the occurrence of short-time severe precipitation. The significant increase in vertical velocity, low-level jet index and atmospheric liquid water content indicate that precipitation is about to begin. There is a good correspondence between the fluctuation of low-level jet index and rainfall intensity. In addition, the increase of 0-1 km vertical wind shear is a good predictor for the occurrence of heavy precipitation. |
Key words: Guiyang; wind profile radar; ground-based microwave radiometer; raindrop size distribution; short-time severe precipitation |