一次局地短时强降水的成因和预报误差分析
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摘要
利用常规气象观测资料、NCEP/NCAR再分析资料和多普勒天气雷达资料,对2016年8月6——8日潍坊一次强对流天气的成因和预报误差进行了分析,结果表明:1) 500 hPa冷涡底部低槽、850 hPa低涡切变线和地面倒槽是主要影响天气系统,数值预报对此次天气过程的影响系统预报偏差大,而预报员对数值预报依赖程度高是此次预报失误的主要原因; 2) 850 hPa以下强的水汽辐合是强降水发生的重要条件,低层辐合和高层辐散配置导致的强垂直上升运动是暴雨产生的动力机制,位势不稳定因中高层的冷空气入侵下沉得以加强; 3)列车效应和强回波维持少动是造成短时强降水的重要回波特征,逆风区的发展和移动对于判断强降水的落区有指示作用,多普勒雷达反演风场中的中尺度辐合线是导致局地强降水发生的直接原因; 4)风廓线雷达水平风场可以连续地反映降水过程中风场垂直结构及其变化,降水发生前探测高度明显升高,中高层冷空气侵入时间与强降水的时段相对应。
The conventional observation data,NCEP/NCAR reanalysis data,and Doppler weather radar data are utilized to analyze the causes and the forecast error of the severe convective weather from 6 to 8 August 2016 in Weifang. The results are listed as below. 1) The trough at the bottom of the cold vortex at 500 hPa,the low vortex with shear line at 850 h Pa,and the surface inverted trough are the main synoptic systems. The numerical forecast has a great deviation of the synoptic systems in this weather process,and the forecaster’s high dependence on it is the main reason for the forecast error. 2) The strong water vapor convergence below 850 hPa is an important condition for the occurrence of the heavy precipitation. The strong ascending motion caused by the configuration of low-level convergence and high-level divergence is the dynamic mechanism of the heavy rainfall. The potential instability is strengthened by the sinking of cold air in the middle and upper levels. 3) The train effect and maintenance of the strong echo are important characters of the heavy rainfall,the development and movement of the upwind area is indicative to the location of the heavy precipitation. The mesoscale convergence line in the retrieval wind field from Doppler radar is a direct cause of the local heavy rainfall. 4) The horizontal wind field from wind profile radar can continuously display the vertical structure of the wind field and its changes during the precipitation process. The detection height obviously increases before the precipitation occurs,and the period of cold air intrusion at middle and high levels corresponds to the period of heavy precipitation.
The conventional observation data,NCEP/NCAR reanalysis data,and Doppler weather radar data are utilized to analyze the causes and the forecast error of the severe convective weather from 6 to 8 August 2016 in Weifang. The results are listed as below. 1) The trough at the bottom of the cold vortex at 500 hPa,the low vortex with shear line at 850 h Pa,and the surface inverted trough are the main synoptic systems. The numerical forecast has a great deviation of the synoptic systems in this weather process,and the forecaster’s high dependence on it is the main reason for the forecast error. 2) The strong water vapor convergence below 850 hPa is an important condition for the occurrence of the heavy precipitation. The strong ascending motion caused by the configuration of low-level convergence and high-level divergence is the dynamic mechanism of the heavy rainfall. The potential instability is strengthened by the sinking of cold air in the middle and upper levels. 3) The train effect and maintenance of the strong echo are important characters of the heavy rainfall,the development and movement of the upwind area is indicative to the location of the heavy precipitation. The mesoscale convergence line in the retrieval wind field from Doppler radar is a direct cause of the local heavy rainfall. 4) The horizontal wind field from wind profile radar can continuously display the vertical structure of the wind field and its changes during the precipitation process. The detection height obviously increases before the precipitation occurs,and the period of cold air intrusion at middle and high levels corresponds to the period of heavy precipitation.
引文
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[2]孙兴池,王业宏,迟竹萍.气旋冷暖区暴雨对比分析[J].气象,2006,32(6):59-65.
[3]杨晓霞,李春虎,李锋,等.山东半岛致灾大暴雨成因个例分析[J].气象科技,2008,36(2):190-196.
[4]史珺,赵玉洁,王庆元,等.风廓线雷达在一次短时暴雨过程中的应用[J].气象与环境科学,2017,40(4):83-89.
[5]董保举,刘劲松,高月忠.基于风廓线雷达资料的暴雨天气过程分析[J].气象科技,2009,37(4):411-414.
[6]杨成芳,王俊.利用单多普勒雷达资料做冷流暴雪的中尺度分析[J].高原气象,2009,28(5):1034-1043.
[7]王宏,王丛梅,高峰,等.承德市两次局地性短时暴雨过程的中尺度特征对比分析[J].气象,2017,43(12):1507-1516.
[8]陈鹏,刘德,周盈颖,等.一次重庆特大暴雨过程的中尺度分析[J].高原气象,2015,34(1):82-92.
[9]王俊.单多普勒天气雷达反演二维风场的方法研究[D].青岛:中国海洋大学,2004.
[10]杨成芳,李泽椿,王俊.用EVAP方法反演冷流暴雪的风场及检验[J].气象学报,2010,68(4):577-583.
[11]陶祖钰.从单Doppler速度场反演风矢量场的VAP方法[J].气象学报,1992,50(1):81-90.
[12]孙莎莎,孙艺,郭俊建,等.ASCAT近岸风在山东沿海的适用性分析[J].海洋气象学报,2017,37(2):90-95.
[13]刁秀广,侯淑梅.4次大暴雨过程雷达径向速度和超低空西南急流特征分析[J].海洋气象学报,2017,37(3):46-53.
[14]杨晓霞.副热带高压边缘连续两次强降水形成机制分析[J].海洋气象学报,2017,37(3):62-72.
[15]张永婧,高帆,于丽娟,等.济南市区短时强降水特征分析与天气分型[J].海洋气象学报,2017,37(3):109-116.
[16]陈艳春,王娜,顾伟宗,等.环渤海区域再分析资料地面风速场的适用性对比分析[J].海洋气象学报,2017,37(1):67-72.
[17]张婷婷,王培涛,王凤娇.一次长寿命超级单体风暴雷达回波特征分析[J].海洋气象学报,2017,37(1):98-103.
[18]吴志彦,闵锦忠,赵海军.冷涡背景下一次强对流过程的卫星水汽图像特征[J].海洋气象学报,2017,37(3):54-61.
[19]杨亦典,白爱娟,彭菊蓉.西南涡影响下汉中盆地一次暴雨过程MCC雷达特征[J].气象科技,2018,46(3):575-583.
[20]吴蕾,董丽萍,王令,等.风廓线雷达在强降水监测预警中的应用研究[J].南京大学学报(自然科学),2014,50(6):865-872.
[21]何平,朱小燕,阮征,等.风廓线雷达探测降水过程的初步研究[J].应用气象学报,2009,20(4):465-470.