文章摘要
赵桂香1,王晓丽1,王一颉1,李莹2.黄河中游地区MCC天气学分型及结构差异分析[J].海洋气象学报,2019,39(1):1-14
黄河中游地区MCC天气学分型及结构差异分析
Synoptic patterns of MCCs and analysis of their structural differences over the middle reaches of the Yellow River
  
DOI:10.19513/j.cnki.issn2096-3599.2019.01.001
中文关键词: MCC  水汽和能量扰动  冷池  边界层入流  结构差异
英文关键词: MCC  water vapor and energy disturbance  cold pool  boundary layer inflow  structural difference
基金项目:国家自然科学基金项目(41475050)
作者单位
赵桂香1,王晓丽1,王一颉1,李莹2 (1.山西省气象台山西 太原 030006 2.山西省气象科学研究所山西 太原 030002) 
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中文摘要:
   利用2005—2017年卫星、实况探测、L波段探空秒数据和NCEP/NCAR FNL 1°×1°再分析等资料,采用天气学和动力诊断分析等方法,对黄河中游地区中尺度对流复合体(mesoscale convective complex,MCC)进行天气学分型,并对其结构特征及差异进行分析。结果表明:1)黄河中游地区MCC主要生成在夏季,多在傍晚至次日凌晨发展成熟,生命史长、移动缓慢,以暴雨及以上量级降水为主,雨强大,地域差异明显。2)依据200 hPa环流形势,将MCC分为3个主型,结合500 hPa形势特点,每个主型下分为不同副型。通过分析不同分型下MCC环境场及物理量空间结构特征及差异,提炼MCC强降水预报关键技术,建立MCC强降水预报物理模型。3)MCC形成在低层比湿和能量扰动的正值中心附近,在低层扰动梯度大值区、靠近正中心的区域发展成熟。扰动正值中心所在高度、中心强度以及正扰动的厚度等物理因子与MCC发展以及降水强度关系密切。4)不同分型下,MCC不同生命阶段云系及环境大气的垂直变化存在明显差异。云顶高度下降,湿层加厚,凝结高度降低,逆温层消失,是MCC达到成熟的先兆信号。5)在200 hPa南亚高压稳定背景下,地面存在次天气尺度冷锋、中尺度高压和冷池;中尺度高压作用明显小于冷池,冷池强度和维持时间与MCC降水强度和持续时间密切相关。在200 hPa深厚低槽和西北急流或急流分支背景下,地面无冷池和中尺度高压形成,低层入流风速和温度梯度的加大是MCC发展成熟的重要因素,中尺度露点锋对MCC强降水的触发作用不可忽视。
英文摘要:
   Based on satellite data, observational data, L-band second-level radiosonde data, and NCEP/NCAR 1°×1° reanalysis data from 2005 to 2017, the synoptic patterns of mesoscale convective complex (MCC) over the middle reaches of the Yellow River are classified, and their structural characteristics are comparatively analyzed by synoptic and dynamic diagnostic analysis. The results are listed as below. 1) In the middle reaches of the Yellow River, MCCs are mainly generated in the summer and generally develop to be mature from dusk till dawn with a long life cycle and slow movements. MCCs mainly produce rainstorm or above-level precipitation with high intensity and significant regional distribution differences. 2) According to the circulation at 200 hPa, the synoptic situation of MCCs are classified into three main patterns, and each main pattern is classified into different secondary patterns according to the circulation at 500 hPa. By comparative analysis of the structural characteristics, environmental conditions, and physical parameters of different MCCs patterns, the key forecasting techniques of heavy MCC precipitation are summarized and the physical models of MCCs are set up. 3) MCCs occur near the positive center of specific humidity and energy disturbance at the lower layer and develop to be mature at areas of great disturbance gradient near the positive center. The development of MCCs and the precipitation intensity have close relationships with the height, intensity, and thickness of the positive disturbance. 4) Though cloud system and vertical variations of ambient atmosphere display obvious differences in different life stages of different MCC patterns, the descent of cloud top, the thickening of moisture level, the decrease of condensation level, and the disappearance of inversion layer are premonitory signals of MCCs developing to be mature. 5) Under the background of stable South Asia high at 200 hPa,there are subsynoptic-scale cold front, mesoscale high, and cold pool on the surface. The impact of mesoscale high is less than that of cold pool, whose intensity and duration are closely related to intensity and duration of MCC precipitation. While under the background of thick upper trough and northwestern jet stream or jet stream branch at 200 hPa, there are no cold pool and mesoscale high on the surface. The increase of inflow wind speed and temperature gradient at the lower layer are the main factors for MCCs developing to be mature. The triggering mechanism of mesoscale dew-point front on heavy MCC precipitation cannot be ignored.
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