Advanced Search
Article Contents

Analysis of a Group of Weak Small-Scale Vortexes in the Planetary Boundary Layer in the Mei-yu Front


doi: 10.1007/s00376-007-0399-9

  • A mei-yu front process in the lower reaches of the Yangtze River on 23 June 1999 was simulated by using the fifth-generation Pennsylvania State University-NCAR (PSU/NCAR) Mesoscale Model (MM5) with FDDA (Four Dimension Data Assimilation). The analysis shows that seven weak small mesoscale vortexes of tens of kilometers, correspondent to surface low trough or mesoscale centers, in the planetary boundary layer (PBL) in the mei-yu front were heavily responsible for the heavy rainfall. Sometimes, several weak small-scale vortexes in the PBL could form a vortex group, some of which would weaken locally, and some would develop to be a meso-$\alpha$-scale low vortex through combination. The initial dynamical triggering mechanism was related to two strong currents: one was the northeast flow in the PBL at the rear of the mei-yu front, the vortexes occurred exactly at the side of the northeast flow; and the other was the strong southwest low-level jet (LLJ) in front of the Mei-yu front, which moved to the upper of the vortexes. Consequently, there were notable horizontal and vertical wind shears to form positive vorticity in the center of the southwest LLJ. The development of mesoscale convergence in the PBL and divergence above, as well as the vertical positive vorticity column, were related to the small wind column above the nose-shaped velocity contours of the northeast flow embedding southwestward in the PBL, which intensified the horizontal wind shear and the positive vorticity column above the vortexes, baroclinicity and instability.
  • [1] WANG Zhi, GAO Kun, 2006: Adjoint Sensitivity Experiments of a Meso- -scale Vortex in the Middle Reaches of the Yangtze River, ADVANCES IN ATMOSPHERIC SCIENCES, 23, 267-281.  doi: 10.1007/s00376-006-0267-z
    [2] WANG Zhi, GAO Kun, 2003: Sensitivity Experiments of an Eastward-Moving Southwest Vortex to Initial Perturbations, ADVANCES IN ATMOSPHERIC SCIENCES, 20, 638-649.  doi: 10.1007/BF02915507
    [3] SUN Jianhua, ZHANG Xiaoling, QI Linlin, ZHAO Sixiong, 2005: An Analysis of a Meso-β System in a Mei-yu Front Using the Intensive Observation Data During CHeRES 2002, ADVANCES IN ATMOSPHERIC SCIENCES, 22, 278-289.  doi: 10.1007/BF02918517
    [4] LIU Jianyong, TAN Zhe-Min, 2009: Mesoscale Predictability of Mei-yu Heavy Rainfall, ADVANCES IN ATMOSPHERIC SCIENCES, 26, 438-450.  doi: 10.1007/s00376-009-0438-9
    [5] CHU Kekuan, TAN Zhemin, Ming XUE, 2007: Impact of 4DVAR Assimilation of Rainfall Data on the Simulation of Mesoscale Precipitation Systems in a Mei-yu Heavy Rainfall Event, ADVANCES IN ATMOSPHERIC SCIENCES, 24, 281-300.  doi: 10.1007/s00376-007-0281-9
    [6] ZHANG Meng, NI Yunqi, ZHANG Fuqing, 2007: Variational Assimilation of GPS Precipitable Water Vapor and Hourly Rainfall Observations for a Meso- Scale Heavy Precipitation Event During the 2002 Mei-Yu Season, ADVANCES IN ATMOSPHERIC SCIENCES, 24, 509-526.  doi: 10.1007/s00376-007-0509-8
    [7] CHU Ke-Kuan, TAN Zhe-Min, 2010: Mesoscale Moist Adjoint Sensitivity Study of a Mei-yu Heavy Rainfall Event, ADVANCES IN ATMOSPHERIC SCIENCES, 27, 1415-1424.  doi: 10.1007/s00376-010-9213-1
    [8] SUN Jianhua, ZHAO Sixiong, XU Guangkuo, MENG Qingtao, 2010: Study on a Mesoscale Convective Vortex Causing Heavy Rainfall during the Mei-yu Season in 2003, ADVANCES IN ATMOSPHERIC SCIENCES, 27, 1193-1209.  doi: 10.1007/s00376-009-9156-6
    [9] Fan Beifen, Ye Jiadong, William R. Cotton, Gregory J. Tripoli, 1990: Numerical Simulation of Microphysics in Meso-β-Scale Convective Cloud System Associated with a Mesoscale Convective Complex, ADVANCES IN ATMOSPHERIC SCIENCES, 7, 154-170.  doi: 10.1007/BF02919153
    [10] Yang Guoxiang, Lu Hancheng, He Qiqiang, 1987: A MESO-α-SCALE STUDY OF MEIYU FRONT HEAVY RAIN-PART II: THE DYNAMICAL ANALYSIS OF RAIN-BAND DISTURBANCE, ADVANCES IN ATMOSPHERIC SCIENCES, 4, 485-495.  doi: 10.1007/BF02656747
    [11] XU Wenhui, NI Yunqi, WANG Xiaokang, QIU Xuexing, BAO Xinghua, JIN Wenyan, 2011: A Study of Structure and Mechanism of a Meso-beta-scale Convective Vortex and Associated Heavy Rainfall in the Dabie Mountain Area Part I: Diagnostic Analysis of the Structure, ADVANCES IN ATMOSPHERIC SCIENCES, 28, 1159-1176.  doi: 10.1007/s00376-010-0170-5
    [12] Xia Daqing, Zheng Liangjie, 1986: NUMERICAL SIMULATION OF THE GENERATION OF MESOSCALE CONVECTTVE SYSTEMS IN LARGE-SCALE ENVIRONMENT, ADVANCES IN ATMOSPHERIC SCIENCES, 3, 360-370.  doi: 10.1007/BF02678656
    [13] Yang Guoxiang, Lu Hancheng, He Qiqiang, 1987: A MESO-α SCALE STUDY OF MEIYU FRONT HEAVY RAIN-PART I: OBSERVATIONAL STUDIES, ADVANCES IN ATMOSPHERIC SCIENCES, 4, 264-277.  doi: 10.1007/BF02915593
    [14] Kelvin S. NG, Gregor C. LECKEBUSCH, Kevin I. HODGES, 2022: A Causality-guided Statistical Approach for Modeling Extreme Mei-yu Rainfall Based on Known Large-scale Modes—A Pilot Study, ADVANCES IN ATMOSPHERIC SCIENCES, 39, 1925-1940.  doi: 10.1007/s00376-022-1348-3
    [15] Zipeng YUAN, Xiaoyong ZHUGE, Yuan WANG, 2020: The Forced Secondary Circulation of the Mei-yu Front, ADVANCES IN ATMOSPHERIC SCIENCES, 37, 766-780.  doi: 10.1007/s00376-020-9177-8
    [16] LIN Yinjing, WANG Hongqing, HAN Lei, ZHENG Yongguang, WANG Yu, 2010: Quantitative Analysis of Meso-β-scale Convective Cells and Anvil Clouds over North China, ADVANCES IN ATMOSPHERIC SCIENCES, 27, 1089-1098.  doi: 10.1007/s00376-010-9154-8
    [17] WANG Pengyun, YANG Jing, 2003: Observation and Numerical Simulation of Cloud Physical Processes Associated with Torrential Rain of the Meiyu Front, ADVANCES IN ATMOSPHERIC SCIENCES, 20, 77-96.  doi: 10.1007/BF03342052
    [18] YANG Shuai, GAO Shouting, Chungu LU, 2015: Investigation of the Mei-yu Front Using a New Deformation Frontogenesis Function, ADVANCES IN ATMOSPHERIC SCIENCES, 32, 635-647.  doi: 10.1007/s00376-014-4147-7
    [19] WANG Yunfeng, WANG Bin, HAN Yueqi, ZHU Min, HOU Zhiming, ZHOU Yi, LIU Yudi, KOU Zheng, 2004: Variational Data Assimilation Experiments of Mei-Yu Front Rainstorms in China, ADVANCES IN ATMOSPHERIC SCIENCES, 21, 587-596.  doi: 10.1007/BF02915726
    [20] Chunguang CUI, Wen ZHOU, Hao YANG, Xiaokang WANG, Yi DENG, Xiaofang WANG, Guirong XU, Jingyu WANG, 2022: Analysis of the Characteristics of the Low-level Jets in the Middle Reaches of the Yangtze River during the Mei-yu Season, ADVANCES IN ATMOSPHERIC SCIENCES.  doi: 10.1007/s00376-022-2107-1

Get Citation+

Export:  

Share Article

Manuscript History

Manuscript received: 10 May 2007
Manuscript revised: 10 May 2007
通讯作者: 陈斌, bchen63@163.com
  • 1. 

    沈阳化工大学材料科学与工程学院 沈阳 110142

  1. 本站搜索
  2. 百度学术搜索
  3. 万方数据库搜索
  4. CNKI搜索

Analysis of a Group of Weak Small-Scale Vortexes in the Planetary Boundary Layer in the Mei-yu Front

  • 1. Department of Earth Sciences, Zhejiang University, Hangzhou 310027,Department of Earth Sciences, Zhejiang University, Hangzhou 310027,Shanghai Meteorology Center, Shanghai 200030

Abstract: A mei-yu front process in the lower reaches of the Yangtze River on 23 June 1999 was simulated by using the fifth-generation Pennsylvania State University-NCAR (PSU/NCAR) Mesoscale Model (MM5) with FDDA (Four Dimension Data Assimilation). The analysis shows that seven weak small mesoscale vortexes of tens of kilometers, correspondent to surface low trough or mesoscale centers, in the planetary boundary layer (PBL) in the mei-yu front were heavily responsible for the heavy rainfall. Sometimes, several weak small-scale vortexes in the PBL could form a vortex group, some of which would weaken locally, and some would develop to be a meso-$\alpha$-scale low vortex through combination. The initial dynamical triggering mechanism was related to two strong currents: one was the northeast flow in the PBL at the rear of the mei-yu front, the vortexes occurred exactly at the side of the northeast flow; and the other was the strong southwest low-level jet (LLJ) in front of the Mei-yu front, which moved to the upper of the vortexes. Consequently, there were notable horizontal and vertical wind shears to form positive vorticity in the center of the southwest LLJ. The development of mesoscale convergence in the PBL and divergence above, as well as the vertical positive vorticity column, were related to the small wind column above the nose-shaped velocity contours of the northeast flow embedding southwestward in the PBL, which intensified the horizontal wind shear and the positive vorticity column above the vortexes, baroclinicity and instability.

Catalog

    /

    DownLoad:  Full-Size Img  PowerPoint
    Return
    Return