【摘要】 实际工作表明,在台风降水云区中,有的站点有大暴雨、有的站点无大暴雨发生。这给单站预报带来较大难度。为了提高降水云区中单站大暴雨预报准确率,本文利用T213客观分析场和预报产品,采用多种物理量综合诊断分析方法,对登陆台风“云娜”在西进途中多站点进行水汽来源、不稳定层结的维持以及次生中尺度辐合等方面的研究,探讨单站大暴雨发生、发展机制和不发生大暴雨的成因。结果表明:单站有大暴雨发生的主要成因是有次级环流出现,如:站点上空∑θse(5+7+8)≥230℃。站点200 hPa为明显的负温度平流,850 hPa为明显的正温度平流。站点高低层均为正涡度中心,且低层的正值大于高层的正值。高低层散度都为负值中心;或高层为正值中心、低层为负值中心。站点垂直运动中心速度值要达-140×10-3hPa/s以下。站点需要有源源不断的充足水汽的供给和辐合。台风中心西北部水汽通量大值区靠近台风中心西部干舌梯度最大处以及风向和风速辐合最大处。在台风降水云区中,当站点满足上述各要素时大暴雨易发生。更多还原

【Abstract】 Heavy rainstorm appears at some stations,while doesn’t appear at the other stations in the precipitation cloud area of typhoon in practice,that bring difficulty to single station forecast.In this paper,in order to improve the accuracy of single station rainstorm forecast in this area,the means of multi-physical parameter synthesis diagnostic analysis is used to analyze the origin of vapor and the maintenance of instability stratification and secondary mid-scale convergence about multi-station typhoon "Rananim" to west,meanwhile,it discusses the occurrence and development mechanism of heavy rainstorm at single station and the reason why it doesn’t occur.The result shows that,the main reason that heavy rainstorm occurs at single station is the appearance of sub-circulation,such as ∑θse_（5+7+8）≥230 ℃ at high latitude over station.It takes on obviously negative thermal advection at 200hPa over station,but positive thermal advection at 850hPa over station.The high and low level of the station are both positive vorticity center,and the value at low level is more than the value at high level.Divergence takes on negative center at each level;or it takes on positive center at high level and negative center at low level.The center value of vertical velocity should be less than 140 10-3 hPa/s at station.Incessant and enough vapor is needed at the station,and vapor convergence is also necessary.The strong water vapor transports over northwest of typhoon center is close with the maximal gradient of dry tongue over typhoon west center,and also lies near to the maximal convergence of wind direction and wind speed.When the factors above appear entirely at station of precipitation cloud area of typhoon,heavy rainstorm is easy to occur.更多还原