刘启汉,陈受钧. 2004. 梅雨锋云带内α-中尺度对流系统周边水汽风的分析[J]. 气象学报, 62(2):237-242, doi:10.11676/qxxb2004.024
梅雨锋云带内α-中尺度对流系统周边水汽风的分析
WATER VAPOR WINDS IN THE VICINITY OF CLOUD BANDS ALONG THE MEIYU FRONT
投稿时间:2003-01-24  修订日期:2003-07-06
DOI:10.11676/qxxb2004.024
中文关键词:  水汽风  梅雨锋云带  中尺度对流系统
英文关键词:Water vapor wind  Meiyu front  MCS
基金项目:973项目:“我国重大天气灾害形成机理及预测理论研究”(G1998040908);863项目:“华南中尺度气象试验”
作者单位
刘启汉 香港科技大学海岸与大气研究中心, 香港 
陈受钧 暴雨监测与预测国家重点实验室, 北京大学大气科学系, 北京, 100871 
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中文摘要:
      应用准静止卫星水汽图像导出的风(简称为水汽风)分析东亚梅雨锋云带内中尺度对流系统(MCS)在对流层上层的流出通道。结果表明梅雨锋云带内MCS有二类流出通道。一类MCS在对流层上层呈现为一个中尺度反气旋。MCS的东部有一支中尺度高空急流,这支中尺度高空急流向东流出后转向南,流入20°N附近的南亚东风急流内,是MCS在对流层上层的主要流出通道。另一类MCS发生在中纬度西风急流的南侧。中纬度西风与MCS南部的偏东北风构成一个反气旋环流带。MCS前方的流出通道(中尺度高空急流)是中纬度西风急流的一个中尺度分支。梅雨锋云带内垂直方向水平风速切变小于1m/(s·100hPa),垂直方向“不通风”有利于云带内MCS的维持。初步分析验证了以前数值模拟得到的中尺度高空急流及其流出通道。
英文摘要:
      Winds obtained by tracking features in satellite water vaporimagery have been used to analyze the upper level outflow in the vicinity of mesoscale convection systems (MCS) along the Meiyu front. Two upper level outflow pat terns have been identified. The first is associated with an upper level mesoscale anticyclone, and the main upper level out flow is seen as a mesoscale upper level jet (mULJ) located to the east of MCS. This mULJ turned to the south and flow into the tropical easterly jet near 20 N, forming a secondary indirect vertical circulation to the south of Meiyu front. In this case, the forcing of the mid-latitude westerly jet is weak. The second kind of upper level outflow was generated just to the south of the extratropic westerly jet. The Meiyu cloud band is associated with an anticyclonic wind belt with mid-latitude westerlies to the north and subtropical easterlies to the south. The upper level out flow (mULJ) appeared as to be a branch of the westerly jet, which flows to the west. A secondary direct circulation is formed along this kind of Meiyu front. The vertical wind shear in the Meiyu cloud band was less than 1 m/(s·100 hPa-1). Weak ventilation in the vertical is helpful for the maint enance of MCSs along the Meiyu front. This primary upper level water vapor wind analyses confirmearlier numerical simulations, which show that the mUL J is the upper level out flow channel over the MCS in the Meiyu cloud band.
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