Secondary Circulations on the Potential Vorticity Staircase: A Theory of Atmospheric Transport

该项目的目标是研究两种基本的不同类型的大气环流之间的相互作用：初级环流，由纬向东西向喷流及其嵌入的Rossby波和Rossby波临界层组成;以及较慢但持续的次级环流，其在很大程度上由与初级环流的射流和波相关的涡流混合驱动，并控制着整个大气层的长期对流传输。虽然初级环流驱动次级环流，但次级环流也通过动量和辐射活性化学物质（特别是二氧化碳、水蒸气和臭氧）的输送来改变初级环流。这项工作广泛建立在以前的NSF支持的研究“位涡阶梯”和大气纬向急流的性质。一个关键的主题将涉及考虑不均匀的涡流混合对高度和纬度的二次环流分布的影响;反过来，二次环流的差分垂直运动使化学示踪剂和位涡梯度变陡。对非平凡垂直结构的重要性和涡动驱动的二次环流在位涡阶梯中的作用的理论研究将得到平流层-对流层和热带-极地动力学耦合以及整个大气中化学示踪剂运输等热点问题的应用的补充。

The goal of this project is to examine interactions between two fundamental and distinct types of atmospheric circulation: primary circulations, consisting of zonal, east-west directed jets together with their embedded Rossby waves and Rossby-wave critical layers; and the slower but persistent secondary circulations, which are driven to a large extent by the eddy mixing associated with the jets and waves of the primary circulations, and which control long-term meridional transport throughout the atmosphere. Although primary circulations drive secondary ones, the latter also modify the former though the transport both of momentum and of radiatively active chemical species, notably carbon dioxide, water vapor, and ozone. The work builds extensively on previous NSF-supported research on the "potential vorticity staircase" and the nature of atmospheric zonal jets. A key theme will involve a consideration of the influence of inhomogeneous eddy mixing on the distribution of secondary circulations in height and latitude; and, in turn, the steepening of chemical tracer and potential vorticity gradients by the differential vertical motions of the secondary circulations. Theoretical investigations into the importance of non-trivial vertical structure and the role of eddy-driven secondary circulations in the potential vorticity staircase will be complemented by applications to topical issues in stratosphere-troposphere and tropical-polar dynamical coupling and the transport of chemical tracers throughout the atmosphere.