| 基于多普勒天气雷达产品的降雪及冻雨综合分析 |
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| 引用本文： | 何彩芬,黄旋旋,卢晶晶.基于多普勒天气雷达产品的降雪及冻雨综合分析[J].应用气象学报,2009,20(6):767-771. |
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| 作者姓名： | 何彩芬 黄旋旋 卢晶晶 |
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| 作者单位： | 1.兰州大学大气科学院, 兰州 730000 |
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| 基金项目： | 宁波市应急联动系统科技专项 |
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| 摘 要： | 利用常规观测资料、探空资料、多普勒雷达资料从天气背景、温度层结及雷达回波特征等方面对宁波2004-2008年的7次降雪过程进行综合分析。结果表明:中层西南气流、低层逆温、低层转偏北风及地面气温低于4 ℃是宁波降雪的必要条件, 西南气流的强弱与范围很大程度上决定降雪强度; 冻雨要求中低空存在高于0 ℃的融化层, 下垫面温度低于0 ℃, 降雪则要求冻结层厚度远大于融化层或者没有融化层; 降雪回波特征中, 回波强度一般低于30dBz, 与降雪量对应关系不明显, 水平和垂直反射率因子梯度小, 结构均匀, 一般谱宽小于4 m/ s, 回波顶高低于6000 m; 零度层亮带所在高度的降低、消失与雨雪转换时间基本吻合, 可以利用零度层亮带高度的变化来判断降水性质的转变; 600 hPa以下零速度线随高度的变化, 对雪止临近预报有一定的指示意义。
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| 关 键 词： | 降雪 冻雨 温度层结 回波特征 零度层亮带 |
| 收稿时间： | 2008-10-07 |
| 修稿时间： | 5/6/2009 12:00:00 AM |
Comprehensive Analysis on Snow and Freezing-rain Events Based on Doppler Weather Radar in Ningbo |
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| He Caifen,Huang Xuanxuan and Lu jingjing.Comprehensive Analysis on Snow and Freezing-rain Events Based on Doppler Weather Radar in Ningbo[J].Quarterly Journal of Applied Meteorology,2009,20(6):767-771. |
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| Authors: | He Caifen Huang Xuanxuan and Lu jingjing |
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| Affiliation: | 1.College of Atmospheric Sciences, Lanzhou University, Lanzhou 7300002.Ningbo Meteorological Bureau, Zhejiang Province, Ningbo 315012 |
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| Abstract: | Seven snow processes in Ningbo are analyzed using conventional observational data,sounding and Doppler radar data in aspects of weather background,temperature stratification,and characteristics of radar echo and so on.The necessary conditions for snowfall are summarized as follows:The temperature inversion in the lower and middle level,the northerly winds in the lower and the surface temperature is below 4 ℃.The strength and influencing ranges of southwest current determine the strength of the snowfall.When freezing rain occurs,it is above 0 ℃ in the lower-middle level forming a melting layer,and the surface temperature is below 0 ℃.During snow weather,the depth of freezing layer is much thicker than the melting layer or there is no melting layer at all.Generally speaking,the reflectivity of snow is less than 30 dBz,the horizontal and vertical gradient of reflectivity is small and the structure is uniform.The spectrum width is below 4 m/s and the echo top is basically below 6000 m.It is found the height of 0 ℃-layer bright band is closely related with the precipitation nature.The distribution of the zero velocity line under the layer of 600 hPa can be divided into three types:Forward-inverse,forward-inverse-forward-inverse ,and inverse-forward-inverse.And the analysis on the distribution of the zero velocity line is of great significance to forecast the end time of snow precipitation. |
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| Keywords: | snowfall freezing rain temperature stratification echo characteristics |
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