Nonlinear Processes in Oceanic and Atmospheric Flows

Presentation

Zonal jets as transport barriers in planetary atmospheres

Author: F.J. Beron-Vera, RSMAS, University of Miami.

Names and affiliation of other authors:
M.G. Brown,* M.J. Olascoaga,* I.A. Rypina,* H. Kocak^ and I.I. Udovydchenkov*
*RSMAS, University of Miami
^Departments of Mathematics and Computer Science, University of Miami

Oral or poster: Oral presentation

Downloadable talk file:

Zonal jets as transport barriers in planetary atmospheres

(NLOA08-FJBV.zip, 14129982 bytes)

Abstract:
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.

*Satellite images from NASA and ESA

Nonlinear Processes in Oceanic and Atmospheric Flows. July 2-4, 2008. Castro Urdiales, Cantabria, Spain.