A model of multiple zonal jets in the oceans : dynamical and kinematical analysis
Berloff, Pavel S.
Kamenkovich, Igor V.
MetadataShow full item record
Multiple alternating zonal jets observed in the ocean are studied with an idealized quasigeostrophic zonal-channel model, with the supercritical, zonal background flow imposed. Both eastward and westward background flows with vertical shear are considered. The underlying nonlinear dynamics is illuminated with analysis of the vertical-mode interactions and time-mean eddy fluxes. Interactions between the vertical modes are systematically studied. The barotropic component of the jets is maintained by both barotropic–barotropic and baroclinic–baroclinic time-mean interactions; thus, the barotropic component of the jets cannot be accurately simulated with a randomly forced barotropic model. The roles of the vertical-mode interactions in driving the baroclinic component of the jets are also characterized. Not only the first but also the second baroclinic mode is found to be important for maintaining the baroclinic component of the jets, whereas the barotropic component of the jets is maintained mostly by the barotropic and first baroclinic modes. The properties of the eddy forcing were systematically studied. It is shown that the baroclinic component of the jets is maintained by Reynolds stress forcing and resisted by form stress forcing only in the eastward background flow. In the westward background flow, the jets are maintained by form stress forcing and resisted by Reynolds stress forcing. The meridional scaling and kinematical properties of the jets are studied as well as the roles of meridional boundaries. The Rhines scaling for meridional spacing of the jets is not generally confirmed, and it is also shown that there are multiple stable equilibria with different numbers of the time-mean jets. It is also found that the jets are associated with alternating weak barriers to the meridional material transport, but the locations of these barriers are not unique and depend on the direction of the background flow and depth. Finally, if the channel is closed with meridional walls, then the jets become more latent but the eddy forcing properties do not change qualitatively.
Author Posting. © American Meteorological Society, 2009. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 39 (2009): 2711-2734, doi:10.1175/2009JPO4093.1.
Showing items related by title, author, creator and subject.
Pettigrew, Neal R. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1980-12)Data from the COBOLT experiment, which investigated the first 12 km off Long Island's south shore, are analyzed and discussed. Moored current meter records indicate that the nearshore flow field is strongly polarized ...
Flagg, Charles Noel (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1977-04)A 37 day long field program was carried out in March 1974 on the New England continental shelf break to study the current and hydrographic structure and variability on the shelf and in the shelf/slope front. A second ...
Gibraltar experiment : a plan for dynamic and kinematic investigations of strait mixing, exchange and turbulence Bryden, Harry L.; Kinder, Thomas H. (Woods Hole Oceanographic Institution, 1986-08)The flow through the Strait of Gibraltar has always held a special fascination for oceanographers. Attempts to understand and measure the strong currents in the Strait stimulated many of the early advances in oceanography ...