Zonal jets as transport barriers in planetary atmospheres
Zonal jets as transport barriers in planetary atmospheres
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DOI：
10.1175/2008jas2579.1
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发表时间：
2008-10-01
影响因子：
3.1
通讯作者：
Udovydchenkov, I. A.
中科院分区：
文献类型：
--
作者：
Beron-Vera, F. J.;Brown, M. G.;Udovydchenkov, I. A.
本文研究了位涡守恒流中的输运障碍和位涡障碍之间的联系，重点是行星大气中的纬向喷流。一个扰动PV阶梯模型用于说明重要的概念。该气流由一系列狭窄的向东和宽阔的向西带状急流组成，具有阶梯PV结构; PV台阶位于向东急流核心的纬度处。本文给出了扰动PV阶梯流中准地转PV守恒方程的数值模拟解。这些模拟结果表明，东向和向西向纬向急流作为强大的纬向输送障碍。令人惊讶的是，向西的喷流，其背景PV梯度消失，作为强大的传输障碍。提供了一个理论解释的基本障碍机制。有人认为，西向纬向急流的核心附近的运输障碍，跨越背景PV梯度是小的，被发现在木星的中纬度天气层和地球的夏季半球的副热带平流层。
The connection between transport barriers and potential vorticity (PV) barriers in PV-conserving flows is investigated with a focus on zonal jets in planetary atmospheres. A perturbed PV staircase model is used to illustrate important concepts. This flow consists of a sequence of narrow eastward and broad westward zonal jets with a staircase PV structure; the PV steps are at the latitudes of the cores of the eastward jets. Numerically simulated solutions to the quasigeostrophic PV conservation equation in a perturbed PV staircase flow are presented. These simulations reveal that both eastward and westward zonal jets serve as robust meridional transport barriers. The surprise is that westward jets, across which the background PV gradient vanishes, serve as robust transport barriers. A theoretical explanation of the underlying barrier mechanism is provided. It is argued that transport barriers near the cores of westward zonal jets, across which the background PV gradient is small, are found in Jupiter's midlatitude weather layer and in the earth's summer hemisphere subtropical stratosphere.