盛杰,林永辉. 2010. 边界层对梅雨锋 β 中尺度对流系统形成发展作用的模拟分析[J]. 气象学报, 68(3):339-350, doi:10.11676/qxxb2010.034
边界层对梅雨锋 β 中尺度对流系统形成发展作用的模拟分析
A numerical simulation and mechanics analysis of the effect of boundary layer on a mesoβconvective system along the meiyu
投稿时间:2009-02-02  修订日期:2009-05-05
DOI:10.11676/qxxb2010.034
中文关键词:  梅雨锋,β 中尺度对流系统, 边界层, 埃克曼非平衡流
英文关键词:Meiyu front, Meso β convective system, Boundary layer, Ekman non balance flow
基金项目:国家自然科学基金(40745026,40875035)、中国气象局行业专项(GYHYQX 2007-6-20)、中国气象科学研究院基本科研业务费专项(2007Y002)和灾害天气国家重点 实验室自主研究专项(2008LASWZ103)
作者单位
盛杰 中国气象科学研究院灾害天气国家重点实验室北京100081
国家气象中心北京100081 
林永辉 中国气象科学研究院灾害天气国家重点实验室北京100081
国家气象中心北京100081 
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中文摘要:
      利用中尺度数值模式MM5对2008年6月9日发生在皖浙赣地区的一次梅雨锋暴雨过程进行 了数值模拟,着重应用高时空分辨率的MM5模式输出资料对引发这次暴雨降水过程的 β 中尺度对流系统(M-β- CS)的发生发展过程进行诊断分析。对这个MCS的中心涡度、散度 的时空演变分析表明其强度的快速增长信号最先出现在边界层,边界层在这个β中尺度 对流系统早期的发生发展过程中起了重要作用;相当位温的演变则显示凝结潜热释放是此次 β中尺度对流系统后期发展的主要物理因子。通过对边界层埃克曼平衡流的进一步分析 发现在这个MCS发展的早期,地形对上升运动的作用基本可以忽略不计,埃克曼抽吸导致的垂直上升运动也仅占边界层整个上升运动的30%左右,真正起主要作用的是边界层中的埃克曼非平衡流调整激发出的次级环流,埃克曼非平衡流向埃克曼平衡流的调整及产生的垂直上升运动可能是导致MCS早期发展的主要物理过程。通过这次模拟诊断分析工作,我们最后得到了以下初步结论:在本次梅雨锋暴雨个例中,MCS的发展前期是依靠边界层内强迫对流启动发展起来,即埃克曼非平衡流向埃克曼平衡流调整过程所引起的次级环流使得MCS在初期发展;当达到一定强度后,可能激发了后来的自由对流即潜热的突然释放,从而使得MCS进一步维持强烈持续的爆发。
英文摘要:
      Using the meso -scale model MM5, the numerical simulation of the evolution of a meiyu front rainstorm occurred over the area around Anhui-Zhejiang-Jiangxi in China on 9 June 2008 is performed and analysed with emphasis on the generation and development of a meso β convective system (MCS) embeded in the meiyu front based on the outputs from the MM5 of high resulution. The analyses of some physical quantities such as vorticity and divergence at the center of the MCS indicate that their first rapid growths happen within the boundary layer that plays a very important role in the earlier development of the meso βconvective system. The evolution of potential equivalent temperature shows that the latent heat release is the main physical process contributed to the subsequent development of the system. To further investigate the developing mechanism of the MCS, the Ekman p umping and Ekman non balance flow were calculated from the model outputs with the result that at the early stage of the MCS, the secondary circulation was mainly driven by the adjustment of Ekman non-balance flow in the boundary layer with no effect of latent heat release and minor orography dynamic lifting as well as minor Ekman pumping contribution (of about 30%) to the ascending motion. Moreover, this secondary circulation may cause the outbreak of latent heat release and trigger the development of the MCS. Finally based on this simulation and diagnostic analysis it is concluded that in this meiyu front rainstorm case, at the early stageof MCS, the secondary circulation caused by the adjustment of the Ekman non balance flow in the boundary layer is responsible for the initial development of MCS, and that the sequent intensification of this secondary circulation favors the outbreak of free convective and latent heat release later so as to maintain the MCS further development.
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