Enhancement in vertical fluxes at a front by mesoscale-submesoscale coupling

dc.contributor.author Ramachandran, Sanjiv
dc.contributor.author Tandon, Amit
dc.contributor.author Mahadevan, Amala
dc.date.accessioned 2015-02-25T19:21:32Z
dc.date.available 2015-06-11T09:09:56Z
dc.date.issued 2014-12-12
dc.description Author Posting. © American Geophysical Union, 2014. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 119 (2014): 8495–8511, doi:10.1002/2014JC010211. en_US
dc.description.abstract Oceanic frontal instabilities are of importance for the vertical exchange of properties in the ocean. Submesoscale, O(1) Rossby number, dynamics are particularly relevant for inducing the vertical (and lateral) flux of buoyancy and tracers in the mixed layer, but how these couple with the stratified pycnocline is less clear. Observations show surface fronts often persist beneath the mixed layer. Here we use idealized, three-dimensional model simulations to show how surface fronts that extend deeper into the pycnocline invoke enhanced vertical fluxes through the coupling of submesoscale and mesoscale instabilities. We contrast simulations in which the front is restricted to the mixed layer with those in which it extends deeper. For the deeper fronts, we examine the effect of density stratification on the vertical coupling. Our results show deep fronts can dynamically couple the mixed layer and pycnocline on time scales that increase with the peak stratification beneath the mixed layer. Eddies in the interior generate skew fluxes of buoyancy and tracer oriented along isopycnals, thus providing an adiabatic pathway for the interior to interact with the mixed layer at fronts. The vertical enhancement of tracer fluxes through the mesoscale-submesoscale coupling described here is thus relevant to the vertical supply of nutrients for phytoplankton in the ocean. A further implication for wind-forced fronts is that the vertical structure of the stream function characterizing the exchange between the interior and the mixed layer exhibits significant qualitative differences compared to a linear combination of existing parameterizations of submesoscale eddies in the mixed layer and mesoscale eddies in the interior. The discrepancies are most severe within the mixed layer suggesting a potential role for Ekman-layer dynamics absent in existing submesoscale parameterizations. en_US
dc.description.embargo 2015-06-11 en_US
dc.description.sponsorship S.R. and A.T. acknowledge financial support from the National Science Foundation (NSF OCE-0928138) and the Office of Naval Research (ONR N00014-09-1-0196, ONR N00014-12-1-0101). A.M. acknowledges funding from the National Science Foundation (NSF OCE-0928617) and the Office of Naval Research (ONR N00014-12-1-0101). en_US
dc.format.mimetype application/pdf
dc.identifier.citation Journal of Geophysical Research: Oceans 119 (2014): 8495–8511 en_US
dc.identifier.doi 10.1002/2014JC010211
dc.identifier.uri https://hdl.handle.net/1912/7169
dc.language.iso en_US en_US
dc.publisher John Wiley & Sons en_US
dc.relation.uri https://doi.org/10.1002/2014JC010211
dc.subject Submesoscale en_US
dc.subject Mixed layer en_US
dc.subject Meso-submeso coupling en_US
dc.subject Deep fronts en_US
dc.title Enhancement in vertical fluxes at a front by mesoscale-submesoscale coupling en_US
dc.type Article en_US
dspace.entity.type Publication
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relation.isAuthorOfPublication.latestForDiscovery 3e6f3266-d95d-4603-96b8-851eb9c7b13c
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