吴芳芳,俞小鼎,王 慧,商 建,周文君. 2019. 一次黄海之滨MCC多尺度结构特征观测研究[J]. 气象学报, ():-, doi:10.11676/qxxb2019.057
一次黄海之滨MCC多尺度结构特征观测研究
A Multi-scale Structural Features Observation Study of MCC on the Coast of the Yellow Sea
投稿时间:2018-08-22  修订日期:2019-03-13
DOI:10.11676/qxxb2019.057
中文关键词:  MCC 飑线 中尺度涡旋 龙卷 强降水 多尺度结构特征
英文关键词:MCC  squall line  mesovortices  tornado  heavy precipitation  multi-scale structure features
基金项目:国家自然科学基金
作者单位E-mail
吴芳芳 江苏省盐城市气象局 wuff102@163.com 
俞小鼎 中国气象局气象干部培训学院 xdyu1962@126.com 
王 慧 上海中心气象台
上海中心气象台 
w_qiuhe@hotmail.com 
商 建 江苏省盐城市气象局 wuff102@163.com 
周文君 盐城市气象局 wuff102@163.com 
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中文摘要:
      2006年7月3日傍晚到4日凌晨,苏北到黄海的一个中尺度对流复合体MCC产生了系列龙卷、直线型对流大风和强降水。本文利用常规高空地面观测、区域自动气象站、卫星云图以及多普勒天气雷达资料详细分析此次MCC产生的天气背景和MCC结构。主要结论如下:1)该MCC高层为分流场对应的强烈辐散,中层为副热带高压西北侧和500hPa东移的短波槽前,地面位于锋面气旋暖区内;该MCC发生在中等到强的对流有效位能CAPE、强的深层(0-6km)和低层(0-1km)垂直风切变环境下;2)该MCC主要垂直环流特征为:近地层东南气流和其上的中低层西南暖湿气流从MCC南部流入到MCC中心,MCC后部对流层中低层和中层为较干冷的西北气流,夹卷进入MCC,导致降水蒸发冷却形成强烈下沉气流,产生带有西北风动量的下沉气流,到地面形成β中尺度冷池,冷池与周边暖湿气流的交界处为β中尺度阵风锋,同时MCC位于对流层中下层到地面部分形成深厚冷池导致的雷暴高压;MCC中高层由于水汽凝结潜热释放加温形成暖心结构,MCC位于对流层中层的主要特征为β中尺度气旋性涡旋对应的中尺度低压,对流层高层存在β中尺度辐散反气旋环流;3)多普勒天气雷达观测揭示出该MCC成熟阶段主要呈现为线性结构,主要构成是一条尺度在150-200km的活跃弓形飑线,还有数条较弱的呈气旋性弯曲的对流雨带,数条雨带旋入共同的涡旋中心,该涡旋中心与地面锋面气旋的中心相对应(重合),同时也是相应MCC的β中尺度气旋的中心,直径在40-60km之间;4)在上述活跃弓形飑线的前侧出现多个中尺度涡旋(mesovortices),4个EF2级龙卷和3个EF1级龙卷都发生在这些中尺度涡旋内,导致龙卷的中尺度涡旋水平尺度在4-5km,旋转速度接近超级单体的强中气旋旋转速度,垂直伸展比超级单体中气旋浅薄,形成机制也与超级单体中气旋有明显差异;5)该MCC成熟阶段的云系尺度为1000km,其中低于220K(-53°C)冷云盖的尺度在400km左右,其内部结构的主要构成是一条150-200km长的活跃弓形飑线,地面β中尺度冷池和阵风锋,沿着弓形飑线前侧出现多个尺度在4-5km的中尺度涡旋,其中部分中尺度涡旋导致尺度只有几十到几百米的EF1和EF2级龙卷,呈现出明显的多尺度结构特征。
英文摘要:
      From the evening of July 3, 2006 to the early morning of the 4th, a mesoscale convective complex MCC from northern Jiangsu to the Yellow Sea produced series of tornadoes, linear convective winds and heavy precipitation. In this paper, the weather background and MCC structure generated by the MCC are analyzed in detail using conventional high-altitude ground observation, regional automatic weather station, satellite cloud image and Doppler weather radar data. The main conclusions are as follows: 1) The MCC generates strong divergence corresponding to the background high-level splitting field. The middle layer is in the northwest side of the subtropical high and the short-wave trough in the eastward shift of 500hPa. The ground is located in the frontal cyclone warm zone, and the medium-to-strong convective effective potential energy CAPE occurs. Strong deep (0-6km) and low (0-1km) vertical wind shear environments; 2) The main vertical circulation characteristics are: The southeast airflow near the surface layer and the mid-lower layer southwest warm and humid airflow flow from the south of the MCC to the MCC center. The rear of the MCC is a relatively dry northwest airflow, which is caught in the MCC, causing the evaporative cooling of the precipitation to form a strong sinking airflow. The northwest wind momentum sinking airflow forms a β mesoscale cold pool to the ground, and the junction of the cold pool and the surrounding warm and humid airflow is the β mesoscale gust front, which also causes the MCC to form cold high pressure in the middle to the lower part of the troposphere (thunderstorm) high pressure); The MCC middle and upper floors are warmed by the latent heat of condensation condensation to form a warm core structure. The MCC is located in the middle part of the troposphere as the β mesoscale cyclonic vortex medium and low pressure, and the upper layer is located near the top of the troposphere as as the β mesoscale anticyclonic divergent flow; 3) Doppler weather radar observation reveals that the MCC maturity stage mainly presents a linear structure, the main composition is an active toxoplasma squall line with a scale of 150-200 km, and several weak convective rain belts with a cyclonic curvature. Several rain belts are screwed into a common vortex center, which corresponds to the center of the ground frontal cyclone (coincidence) and is also the center of the β mesoscale cyclone of the corresponding MCC, with a diameter of 40-60 km; 4) Multiple mesovortices appear on the front side of the active toxoplasma squall line, and four EF2 tornadoes and two EF1 tornadoes occur in these mesovortices, resulting in the mesovortices horizontal scale of the tornado is 4-5km, the rotation speed is close to the strong medium cyclone rotation speed contained in the super monomer, and the vertical extension is shallower than the cyclone in the super monomer, and the formation mechanism is also significantly different from the cyclone in the super monomer; 5) The cloud system at the mature stage of MCC is 1000km, and the scale of the cold cloud cover below 220K (-53°C) is about 400km. The main structure of the internal structure is a 150-200km long active toxoplasma squall line. The ground β mesoscale cold pool and the gust front, and a mesoscale vortex with a plurality of scales of 4-5 km along the front side of the toxoplasma squall line, Some mesoscale vortices lead to EF1 and EF2 tornado scales of only tens to hundreds of meters, showing obvious multi-scale structural features.
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