γ中尺度单体合并在昭通小河镇“2010.7.13”灾害性天气中的特征分析

Characteristic Analysis on Meso-γ Cells Merging in Disastrous Weather Occurred in Xiaohe Town of Zhaotong in Yunnan Province on July 13,2010

低纬度高原特殊地形影响下的云和降水与其它地区相比有一些独特的情形,中-γ尺度暴雨就是特征鲜明的一类,由此系统引发的降水突发性较强,常造成灾害。利用常规高空资料、卫星资料、加密乡镇雨量站资料和新一代多普勒雷达资料,对2010年7月13日云南昭通小河镇灾害性天气分析发现:短时性、高强度,在降水开始的1 h左右就达到暴雨量级,是此次过程的降水特点;中低层风向辐合、高冷低暖、整层潮湿,低层偏南暖湿气流输送水汽及对流不稳定能量堆积,以及边界层辐合线的触发提供了中尺度天气背景;强中尺度对流系统(MCS)是此次暴雨形成的云图中尺度特征;多普勒雷达观测资料分析表明,镶嵌在中-β尺度上的中-γ尺度单体为形成强降水的直接影响系统,该类系统以"单体合并型"和"自壮大升尺度型"居多,且"单体合并型"占较大比例;单体组织化合并可能是部分这类暴雨的触发与维持机制之一。

There are some unique features about clouds and precipitation by influence of the low latitude plateau.Mesoscale-γ rainstorm is of such kind of distinct characteristic.With the conclusion of a burst activity,such rainfall always creates havoc.Based on conventional altitude data,satellite data,encrypted rainfall station and Doppler radar（new generation） detection data,disastrous weather occurred in Xiaohe town of Zhaotong on July 13,2010 is analyzed.Results show that the precipitation process is characterized by short-term and high-intensity which reached rainstorm magnitude in the first hour of the precipitation.Mesoscale weather background is provided by middle-lower wind direction convergence,upper-level cold and lower-level warm flow,total damp atmosphere,south-southwest air stream transported plenty of heat and moisture for the storm,heating and wetting weakened the stability of the air,and boundary convergence line.MCS is the mesoscale system of cloud picture feature which caused this process.Meso-γ with meso-β system is the direct influence system of radar data characters.Meso-γ cells merging pattern and large scale pattern by strengthen itself are the main Meso-γ system types,especially latter.Meso-γ cells merging organized is probably one of the mechanisms for initialization and maintenance.