一次大暴雨过程的湿Q矢量比较分析

Comparative Analysis of Wet Q Vectors of a Continued Heavy Rain

结合2005年7月18～19口出现在青藏高原东侧的一次大暴雨天气过程，对改进前（Q^＊）后（Q^q）两种非地转湿Q矢量的散度和锋生函数进行了比较诊断分析。结果表明：①改进后的掣矢量散度辐合场在位置、强度及走向上对暴雨区的反映都较改进前的Q^＊矢量更为准确。低层大气强迫为产生暴雨区上升运动的主要强迫作用，在不稳定的层结下使大气加速上升而产生强对流。②包含了所有非绝热效应的湿Q矢量锋生函数对暴雨中心和雨区走向的反映更准确，锋生作用更强。当出现一定程度降水后，由于大量不稳定能量的释放，锋消作用明显。

A comparative diagnosis of the divergence and frontogenesis fields of the ageostrophic wet Q-vector （Q^＊） and the improved ageostrophic wet Q vector （Q^q） is made for a torrential rain process over the eastern Qinghai-Xizang Plateau occurred on 18 to 19 July 2005. The results show： （1） The convergence field of the Qq reflects the intensity and area of the heavy rainfall more precisely than that of Q^＊. The lower-level atmospheric forcing is the main driving factor of the vertical motion in the heavy rain area, which made the updraft accelerate under the instability stratification and caused strong convection. （2） The frontogenesis function of Q^q with all diabatic heating effects reflects the center and area of the heavy rainfall more precisely and has stronger frontogenesis effect. After the rainfall, due to the release of instable energy, there appeared evident frontolvsis.