| 天津城区暴雪的环流形势与雷达特征分析 |
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| 引用本文：胡玲，刘锦，东高红，等..天津城区暴雪的环流形势与雷达特征分析[J].气象与环境科学,2020,43(1):34-42.Hu Ling,Liu Jin,Dong Gaohong,et al..Analysis on the Circulation Situation and Radar Characteristics of Snowstorm in Tianjin City[J].Meteorological and Environmental Sciences,2020,43(1):34-42. |
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| DOI：doi:10.16765/j.cnki.1673-7148.2019.04.005 |
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| 中文摘要:利用常规观测资料和天津新一代天气雷达资料,对20022017年发生在天津城区的4次暴雪天气过程进行了分析，结果表明：4次暴雪过程均属于回流型降雪，但环流形势和影响系统却不尽相同；暴雪主要产生在500 hPa和700 hPa高空槽、850 hPa切变线东移的形势下；水汽主要来源于700 hPa西南急流及850 hPa低空和925 hPa超低空急流的水汽输送。回流东北风在天津地区形成冷空气垫，有利于西南暖湿气流的爬升，加强了地面的动力抬升作用。通过对暴雪过程的雷达径向速度场分析看到，暴雪过程具有零速度等值线闭合特征，此特征是冬季降雪过程独有的特征，反映了近地面层与中高层之间的风切变，闭合越完整表明切变越强烈，可以直观地预警暴雪量级。另外，高仰角上中尺度辐合线维持时间的长短与降雪量之间对应关系较好，可以作为预警降雪量级的一个指标。VWP图上从观测到西北风出现到降雪结束平均需要12 h，这可以作为暴雪结束时间的预报指标。 |
| 中文关键词:暴雪 环流形势 回流 雷达特征 |
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| Analysis on the Circulation Situation and Radar Characteristics of Snowstorm in Tianjin City |
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| Abstract:Based on the conventional observation data and the Tianjin CINRAD/SA Radar data,the four snowstorm processes that occurred in Tianjin city during 20022017 are analyzed.The results show that all the four snowstorm processes belong to back flow snowfall,but their circulation situation and influence systems are different.Snowstorms are mainly generated in the situation of 500 hPa and 700 hPa troughs with the 850 hPa shear line moving eastward.Water vapor is mainly sourced from the moisture transmission of 700 hPa southwest jet,850 hPa low altitude jet and 925 hPa ultra low altitude jet.The back flow northeast wind forms cold air cushion in Tianjin area,which is conducive to the rise of the warm and wet air flow in southwest and strengthens the dynamic uplift of the ground.Through analyzing of the radar radial velocity fields in the snowstorm processes,we can see that the snowstorm processes have the characteristics of zero velocity isoline closing,which is unique to the winter snowfall process,reflecting the wind shear between the near surface layer and the middle upper layer.The more complete the closing,the stronger the wind shear.Thus,the magnitude of the snowstorm can be intuitively estimated.In addition,there is a good relationship between the duration of meso scale convergence line and the amount of snow fall at high elevation angle,so it can be used as an indicator for the early warning of the snowstorm magnitude.On the VWP chart,it takes an average of 12 h from the observed northwest wind to the end of the snowfall,which can be used as a prediction indicator for the end timing of snowstorm. |
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