青藏高原东侧一次连续大暴雨过程湿Q矢量分析

Wet Q-Vector Analysis of a Continued Heavy Rain Process over the Eastern Qinghai-Xizang Plateau

利用常规探空和地面实测资料,对2005年7月18—19日出现在青藏高原东侧的一次区域性大暴雨天气过程进行了非地转湿Q矢量诊断分析。结果表明: (1)暴雨出现在湿Q矢量散度负值中心激发的非地转上升气流区附近,在强降水期散度负值中心达到最强,范围较窄,与暴雨区对应得较好。(2)700hPa湿Q矢量涡度正值中心与其散度负值中心重叠的区域是中尺度低值系统发展的有利区域,与暴雨区对应。(3)700hPa湿Q矢量锋生中心可以对应12小时后的暴雨区;当有不稳定能量大量释放后,有锋消作用,暴雨将逐渐减弱。

Based on the routine observations, an ageostrophic wet Q-vector diagnosis of a heavy rain process over the eastern Qinghai-Xizang Plateau during 18-19 July 2005 is made. The results show as follows： （1） The heavy rain occurred in the updraft area triggered by the convergence center of the wet Q-vector. The convergence center is narrow and strong during the heavy precipitatioru （2） The superposition area of the center of the positive vorticity and the convergence center of the wet Q-vector at 700hPa is advantageous to the mesoscale systerru It corresponds well to the heavy rain area. （3） The center of frontogenesis at 700hPa corresponds to the heavy rain area after 12 hours. After the instability energy is released largely, the air mass has frontolysis, and the heavy rain decreases gradually.