2014年7月14日高原低涡降水过程观测分析  

Characteristics of a Plateau Vortex Precipitation Event on 14 July 2014

作　　者：赵平[1] 袁溢 Zhao Ping Yuan Yi(State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081)

机构地区：[1]中国气象科学研究院灾害天气国家重点实验室,北京100081

出　　处：《应用气象学报》2017年第5期532-543,共12页Journal of Applied Meteorological Science

基　　金：公益性行业(气象)科研专项(GYHY201406001)

摘　　要：利用第三次青藏高原大气科学试验的多种雷达、雨滴谱仪以及MODIS卫星观测资料、常规气象站地面和高空观测资料,针对2014年7月14日发生在青藏高原中部那曲地区的一次降水过程,研究了降水的时空变化特征,触发不同阶段降水的天气尺度和中尺度环流系统以及相关的云降水物理特征。从降水演变特征看,这次降水过程包括3个阶段,即发生在下午的强降水阶段和夜间的两个弱降水阶段。从影响系统看,下午的降水主要由天气尺度的高原低涡发展引起,此时那曲位于低涡中心前部的中尺度辐合线上;发生在晚上的降水主要与高原低涡前部的暖湿东南气流爬越地形有关,东南气流为产生降水提供了有利的水汽、大气不稳定和浅薄的动力抬升条件。从云降水微物理特征看,高原低涡降水初期,低涡前部的上升运动深厚,对流发展明显,而后期的对流性减弱。东南气流爬坡引起的地形降水表现出层状云降水的特征,高原低涡降水的雨滴谱分布较宽(0.3~4.9 mm),而夜间降水过程的雨滴谱分布较窄(0.3~2.1 mm)。Using various radar and disdrometer datasets from periment, MODIS data, surface and sounding datasets, the Third Tibetan Plateau Atmospheric Science Extemporal and spatial variations of one rainfall event on 14 July 2014 over Naqu in the central Tibetan Plateau is analyzed, the synoptic and meso-scale atmospheric circulations, and associated cloud-rainfall microphysical characteristics are also investigated. This rainfall process includes three stages, namely, the first stage with heavy rainfall starts in the afternoon （1400 BT） and ends at 1800 BT 14 July, the peak intensity of hourly precipitation occurs during 1500-- 1600 BT, which reaches 2.1 mm · h-1. The second stage begins at 1900 BT, and the precipitation intensity weakens prominently compared with the first stage. The third stage is from 2200 BT 14 July to 0100 BT 15 July with a weaker precipitation intensity. Rainfall during the first stage is mainly produced and the formation of a meso-scale convergence line in by the development of a synoptic-scale plateau vortex front of the vortex circulation center. The radar echo propagates northeastward, and this stage ends with the weakening of the plateau vortex. Rainfall at night is mainly associated with the warm and moist southeasterly flow passing over the topography near Naqu, which provides favorable conditions of the atmospheric moisture, instability, and shallow dynamic elevation. With the intrusion of the low-level northeasterly flow, the radar echo generally propagates southeastward. Moreover, during the earlier stage of the first rainfall stage, the ascending motion is deep over the east of the vortex, exceeding 3 m · s-1 between 3 km and 11 km ahove the ground level, which indicates the remarkable development of convections. During the later stage, rainfall is mainly produced by strati- form clouds, with a higher cloud top. Rainfall at night is mainly caused by stratiform clouds. The raindrop size distribution is wider （0.3--4.9 mm） than that size of 0.3--2.1 mm in the topographic rainfal

关 键 词：高原低涡 地形云降水 云物理特征 

分 类 号：P458.121[天文地球—大气科学及气象学]