一次梅雨锋暴雨过程的中尺度特征分析

利用中尺度非静力平衡模式WRF-V2.1对2007年7月7-8日江淮地区一次梅雨锋暴雨过程进行数值模拟,分析其中的中尺度重力波(MGW)特征,并运用拉格朗日Rossby数(Ro)来诊断非平衡流特征.研究表明:这次暴雨过程中的中尺度重力波波长约为56～75 km,相速约12～19 m·s~(-1);在有利的大尺度环流形势下,地转调整机制是MGW产生的首要机制,Wave-CISK和地转调整为波动传播提供了充足的能量,使MGW在具有波导结构的大气中维持了相当长的时间;满足舶指标的不平衡运动区与重力波活动区十分接近,它对波动产生的时间和区域方面有一定的指示作用.

Mesoscale characteristics analysis of a Meiyu front heavy rain process

A Meiyu front heavy rain process occurred in Jiang-Huai area basin during July 7-8, 2007 is simulated with the mesoscale numerical model WRF-V2.1. The detailed diagnostic analyses are performed upon the mesoscale gravity-wave features, and the Lagrangian Rossby number (Ro) is evaluated for its usefulness in the diagnostic of unbalanced flow. The MGW's wavelength is about 56 -75 km, and the propagation speed is about 12 -19 m·s~(-1). The geostrophic adjustment caused by the unbalanced flow is the key mechanisms to initiate the MGW. Enough wave energy which is provided by Wave-CISK mechanism and geostrophic adjustment make MGW maintaining for a longer time, while there is a wave ducting structure in the atmosphere. The Lagrangian Rossby number Ro≥0. 5 shows clear indication of the MGW initiation region and propagation direction.