基于多普勒天气雷达产品的降雪及冻雨综合分析
Comprehensive Analysis on Snow and Freezing-rain Events Based on Doppler Weather Radar in Ningbo
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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。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 6000m. 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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[1] 何彩芬, 姚秀萍, 胡春蕾. 一次台风前部龙卷的多普勒天气雷达分析. 应用气象学报, 2006, 17(3): 67-72. http://qk.cams.cma.gov.cn/jams/ch/reader/view_abstract.aspx?file_no=20060363&flag=1 [2] 朱龙彪, 郑铮, 何彩芬. 0414号台风"云娜"多普勒雷达探测. 应用气象学报, 2005, 16(4): 500-508. http://qk.cams.cma.gov.cn/jams/ch/reader/view_abstract.aspx?file_no=20050463&flag=1 [3] 何彩芬, 朱龙彪, 董杏燕. 宁波夏季强对流和台风短时暴雨的雷达回波特征对比分析. 气象, 2005, 31(7): 59-61. http://cpfd.cnki.com.cn/Article/CPFDTOTAL-ZJDX200611001144.htm [4] 苗爱梅, 安炜, 刘月丽, 等. 春季一次暴雪过程的多普勒雷达动力学诊断. 气象, 2007, 33(2):57-61. http://www.cnki.com.cn/Article/CJFDTOTAL-QXXX200702008.htm [5] 王丽荣, 汤达章, 胡志群, 等. 多普勒雷达的速度图像特征及其在一次降雪过程中的应用. 应用气象学报, 2006, 17(4): 452-458. http://qk.cams.cma.gov.cn/jams/ch/reader/view_abstract.aspx?file_no=20060476&flag=1 [6] 张腾飞, 鲁亚斌, 张杰, 等. 2000年以来云南4次强降雪过程的对比分析.应用气象学报, 2007, 18(1):64-72. http://qk.cams.cma.gov.cn/jams/ch/reader/view_abstract.aspx?file_no=20070112&flag=1 [7] 梁卫芳, 刘珍芳, 江敦双, 等. 青岛一次中到大雪过程的综合分析. 气象, 2006, 32(1): 89-94. http://www.cnki.com.cn/Article/CJFDTOTAL-QXXX200601016.htm [8] 东高红, 张志茹, 李胜山, 等. 一次大雪天气过程的多普勒雷达特征分析. 气象, 2007, 33(7): 75-81. http://cpfd.cnki.com.cn/Article/CPFDTOTAL-ZGQX200610007110.htm [9] 杨柳, 苗春生, 寿绍文, 等. 2003年春季江淮一次暴雪过程的模拟研究. 南京气象学院学报, 2006(6): 379-384. http://www.cnki.com.cn/Article/CJFDTOTAL-NJQX200603013.htm [10] 王东勇, 刘勇, 周昆, 等. 2004年末黄淮暴雪的特点分析和数值模拟. 气象, 2006, 32(1): 30-35. http://www.cnki.com.cn/Article/CJFDTOTAL-QXXX200601006.htm [11] 杨成芳, 李泽椿, 周兵, 等. 渤海南部沿海冷流暴雪的中尺度特征. 南京气象学院学报, 2007(12): 857-865. http://www.cnki.com.cn/Article/CJFDTOTAL-NJQX200706018.htm [12] 李建华, 崔宜少, 单宝臣. 山东半岛低空冷流降雪分析研究. 气象, 2007, 33(5): 49-54. http://www.cnki.com.cn/Article/CJFDTOTAL-QXXX200705006.htm [13] Roy Rasmussen, Michael Dixon, Steve Vasiloff, et al. Snow now casting using a real-time correlation of radar reflectivity with snow gauge accumulation. JAppl Meteor, 2003, 42: 20-36. doi: 10.1175/1520-0450(2003)042<0020:SNUART>2.0.CO;2 [14] 张培昌, 杜秉玉, 戴铁丕. 雷达气象学. 北京: 气象出版社, 2001: 314-320. [15] 章国材, 矫梅燕, 李延香, 等. 现代天气预报技术和方法. 北京: 气象出版社, 2007.