On latency of multiple zonal jets in the oceans
Berloff, Pavel S.
Karabasov, S. A.
Farrar, J. Thomas
Kamenkovich, Igor V.
MetadataShow full item record
Most of the nearly zonal, multiple, alternating jets observed in the oceans are latent, that is, their amplitudes are weak relative to the ambient mesoscale eddies. Yet, relatively strong jets are often observed in dynamical simulations. To explore mechanisms controlling the degree of latency, we analyse solutions of an idealized, eddy-resolving and flat-bottom quasigeostrophic model, in which dynamically generated mesoscale eddies maintain and interact with a set of multiple zonal jets. We find that the degree of the latency is controlled primarily by the bottom friction: the larger the friction parameter, the more latent are the jets; and the degree of the latency is substantial for a realistic range of the oceanic bottom friction coefficient. This result not only provides a plausible explanation for the latency of the oceanic jets, but it may also be relevant to the prominent atmospheric multiple jets observed on giant gas planets, such as Jupiter. We hypothesize that these jets can be so strong because of the relative absence of the bottom friction. The mechanism controlling the latency in our solutions is understood in terms of the changes induced in the linear eigenmodes of the time–mean flow by varying the bottom friction coefficient; these changes, in turn, affect and modify the jets. Effects of large Reynolds numbers on the eddies, jets, and the latency are also discussed.
Author Posting. © Cambridge University Press, 2011. This article is posted here by permission of Cambridge University Press for personal use, not for redistribution. The definitive version was published in Journal of Fluid Mechanics 686 (2011): 534-567, doi:10.1017/jfm.2011.345.
Showing items related by title, author, creator and subject.
Ralph, Elise A. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1994-09)The thesis addresses the applicability of traditional hydraulic theory to an unstable, mid-latitude jet where the only wave present is the Rossby wave modified by shear. While others (Armi 1989, Pratt 1989, Haynes et ...
Radiation and dissipation of internal waves generated by geostrophic motions impinging on small-scale topography Nikurashin, Maxim (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2009-02)Observations and inverse models suggest that small-scale turbulent mixing is enhanced in the Southern Ocean in regions above rough topography. The enhancement extends 1 km above the topography suggesting that mixing is ...
Assimilation of altimeter data in a quasi-geostrophic model of the Gulf Stream system : a dynamical perspective Capontondi, Antonietta (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1993-02)The dynamical aspects involved in the assimilation of altimeter data in a numerical ocean model have been investigated. The model used for this study is a quasi-geostrophic model of the Gulf Stream region. The data that ...