应用云迹风资料同化的江南飑线模拟试验

运用WRF模式对2006年6月10日发生在浙江地区的一次飑线过程进行了数值模拟及云迹风资料同化实验研究.将常规测站、自动站资料同化试验和加入了云迹风资料的试验进行比较,结果表明,用WRF模式进行同化模拟,较好地再现了此次江南地区飑线的发生、发展、维持和消亡过程.主要分布在对流层高层的云迹风资料能有效地改善高空风场质量,在模式中增加了云迹风资料之后,使模拟的雷达反射率图像增加了清晰度,原来有些地段较为零星逗点状的反射率图像可被连成带状,尤其明显的是模拟的主降水强度和落区与实际降水分布更加接近;模拟也改变了后半程的大风区的分布并增强了风速,比控制试验稍接近于实况,且略缩小了降水和大风的虚假区域.同时,通过不同质量控制阈值的云迹风模拟试验比较发现,进入模式的云迹风数量与模拟效果并不是简单的线性正相关,因此,在云迹风资料的运用上,质量控制对模拟有一定的影响,恰当地应用云迹风资料同化能在一定程度上改善强对流系统的数值模拟,对提高降水、大风等预报质量是较有效的途径.

Assimilation study of squall line in the south of Yangtze River using cloud motion wind data

In order to study the effect of cloud motion wind（CMW） data assimilation on heavy convection simulation,a squall line weather process on 10th Jun,2006 in the south of Yangtze River is simulated by WRF model.The results show that the simulations with CMW data are closer to the observation,better to reappear the birth,development and death of the squall line.Cloud motion winds mostly on the upper troposphere can availably modify the quality of upper wind and initial analysis field.But it needs quality control before using the CMW data for some stations taking on disorder.It is very important to guarantee the high performance in data processing.Several numerical simulation experiments with different schemes through setting different thresholds are performed indicating that it＇s not a simple linear correlation between quantity of CMW data absorbed in the model and the effect of simulation,as more CMW data will be adopted,and more inaccurate information will be mixed in.Evidence shows that there is a great improvement in the simulation for forecast through adjustment of the wind field by incorporating the CMW data into a numerical model because it remedied the fail to make forecast of meso and micro-scale weather systems which was caused by insufficient observation stations.By means of integrating with CMW data,it can make the radar reflectivity more clearly and can connect some scattered reflectivity with zonal image.And the main rainstorm focus is simulated well in the experiment of combining with the U,V of infrared window channel and water vapor absorption channel.Especially it＇s closer to observation for the range and intensity of rainfall.Meanwhile,it＇s more semblable with observation than control experiment for the gale area at the second half simulation and also improves wind speed,as well as can minish the inveracious region of rainfall and gale after applying the CMW data to the model.It＇s beyond dispute that CMW data assimilation could improve the simulation ability of WRF model.In such a way as to get more accurate CMW data assimilated,there is no doubt that the use of CMW data is an important approach to enhance the rainfall and wind forecast in operation and research work.