Alternating Zonal Jets in the Oceans: A Laboratory Study.

摘要

This paper investigates anisotropic oceanic features referred to as "zonal jets", zonal meaning that velocity alternates in the east-west direction with latitude. Zonal jets, as predicted by turbulence theory, were recently observed by satellite altimetry in the world ocean and were observed separately in numerical models of the ocean. This study is focused on understanding the mechanisms involved in the formation of alternating zonal jets. Experiments were carried out on a rotating table in the geophysical fluid dynamics laboratory run by Peter Rhines at the University of Washington in Seattle. A cylindrical tank placed on the table and filled with saline water provides a simplified and controlled environment for modeling the dynamics of oceanic circulation. The experiments performed for this study demonstrate a mechanism where the jets result from the development of beta-plumes originating from baroclinic instability at the eastern boundary of an ocean. The underlying dynamics include the propagation of linear and nonlinear basin scale Rossby waves. The dynamic flow fields were measured by Altimetric Imaging Velocimetry (AN) and optical thickness methods.