The Role of a Polar/Subtropical Jet Superposition in the May 2010 Nashville Flood
The Role of a Polar/Subtropical Jet Superposition in the May 2010 Nashville Flood
复制标题
极地/副热带急流叠加在 2010 年 5 月纳什维尔洪水中的作用
DOI：
10.1175/waf-d-13-00124.1
复制
发表时间：
2014
影响因子：
2.9
通讯作者：
Jonathan E. Martin
中科院分区：
文献类型：
--
作者：
A. Winters;Jonathan E. Martin
从极地和副热带急流叠加及其对次级非地转环流的影响的角度，分析了2010年5月1 - 3日田纳西州纳什维尔洪水第二天向极水汽通量增加的贡献。采用索耶-埃利亚森环流方程的分析表明，归因于急流的极向水汽通量增加了近120%，在事件的第二天之前，以响应叠加急流的非地转环流，有助于进一步燃料的生产暴雨。与叠加急流相关联的完整索耶-埃利亚森环流被进一步划分为地转分量和非绝热分量。地转强迫推动对流层中部上升，促进了深对流的产生和创纪录的降雨。非绝热分量通过强迫对流层低层上升和强烈的对流层低层极向水汽通量，提供了热带水汽和深对流环境之间的联系。由于叠加急流的性质是在热带或副热带空气的极向边缘发展的，因此建议次级环流的这两个分量强迫之间的这种相互加强的相互作用可能是高影响天气事件中叠加急流结构参与的常规特征。
Contributions to the increased poleward moisture flux that characterized the second day of the 1‐3 May Nashville, Tennessee, flood of 2010 are examined from the perspective of polar and subtropical jet superposition and its influence on the secondary ageostrophic circulation. Employing the Sawyer‐Eliassen circulation equation, the analysis reveals that the poleward moisture flux attributed to the jet increased nearly 120% prior to the second day of the event in response to the superposed jet’s ageostrophic circulation, helping to further fuel the production of heavy rainfall. The full Sawyer‐Eliassen circulation associated with the superposed jet is further partitioned into its geostrophic and diabatic components. The geostrophic forcing drove midtropospheric ascent that fueled the production of deep convection and the record rainfall. The diabatic component, through forcing lower-tropospheric ascent and vigorous lowertropospheric poleward moisture flux, provided the link between the tropical moisture and the deep convectiveenvironment. Since superposed jets, by their nature, develop on the poleward edge of the tropical or subtropical air, it is suggested that such a mutually reinforcing interaction between these two component forcings of the secondary circulation may routinely characterize the involvement of superposed jet structures in high-impact weather events.