华北地区一次中-α尺度强涡旋发展的数值模拟

A THREE DIMENTIONAL NUMERICAL MODELING FOR THE DEVELOPMENT OF A MESO-α SCALE STRONG VORTEX IN NORTH CHINA

本文用 PSU/NCAR-MM4三维中尺度模式模拟一次华北地区冷锋越过太行山进入华北平原后,中尺度气旋的发展过程及其三维结构。当锋区移过太行山后可以形成若干个中-α尺度涡旋,当涡旋进入华北平原时,涡旋的低层位于干线前缘的湿中心处,同时由于有低层冷空气的侵入,涡旋处在很强斜压状态中。最大正涡度区位于涡旋前部,强辐合是该中尺度系统涡度加强的重要原因。

When a cold front passes through the Taihang mountain down to the north China plain,it isfound that there are several meso-α scale vortexes occurred in the frontal zone at the same time.The developing process and the 3-dimentional structure of a mesoscale cyclone have been simulat-ed using a 3-dimentional numerical model.The vortex in the lower troposphere is located at themoisture center in front of the dry line,where exists a strong dynamic instability and baroclinic.The maximum positive vorticity center occurs in the ahead of the vortex.The intensification ofthe mesoscale vortex caused by the strong convergence is an important role of heavy rainfall insummer.