一次强沙尘暴过程的动量下传诊断分析

摘要

动量下传对沙尘暴的发生发展起着十分重要的作用.选取2002年3月18-22日发生在我国华北地区的一次强沙尘暴过程,利用中尺度气象模式MM5V3.7输出的高分辨率动力协调资料,应用位涡理论详细探讨了沙尘暴发生发展的动量下传过程.结果表明:①蒙古气旋是此次强沙尘暴的主要影响系统；大风与干燥低湿是风蚀起沙的前提条件.②沙尘暴过程中,位涡沿等熵面下滑是高、低层动量交换的重要环节,揭示了沙尘暴动量下传的物理机制.%The mesoscale meteorological model (MM5V3. 7) is used to simulate a strong sand and dust storm (SDS) process in North China from 18 to 22 March 2002. With the high-resolution data from MM5V3.7, the PV-theory (potential vorticity) is applied to reveal the mechanism of downward momentum transport. The results show that: (1) the Mongolia cyclone was the main weather system during this strong SDS process, and gales and dryness were the preconditions of the wind erosion; (2) the downward transportation of potential vorticity along the iso-entropy surface was the most important process during the SDS, which clearly reveals the mechanism of downward momentum transport.