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Submesoscale activity over a numerical Argentinian shelf

Grant number: 08/05636-2
Support type:Regular Research Grants - Publications - Scientific article
Duration: August 01, 2008 - January 31, 2009
Field of knowledge:Physical Sciences and Mathematics - Oceanography
Principal Investigator:Edmo José Dias Campos
Grantee:Edmo José Dias Campos
Home Institution: Instituto Oceanográfico (IO). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Submesoscale activity over the shelf and slope of the southwestern Atlantic shelf is investigated by means of high resolution primitive equation numerical solutions. The solutions reveal energetic turbulent activity at scales O(5 km) in fall and winter that is linked to baroclinic mixed layer instability. The air-sea heat flux responsi-ble for (i) deepening the upper ocean boundary layer (at these seasons) and (ii) maintaining a cross-shelf background density gradient is the key environmental parameter controlling submesoscale activity. Dynamical implications of submesoscale turbulence are investigated. We provide quantitative estimates for its mixing efficiencyby computing a diffusivity coefficient. Values above 30 m2 s1 cover most of the shelf, at the exception of localized regions where shallow bathymetry seems to inhibit the development of submesoscale. Densely distributed surface fronts and horizontal convergences lead to rapidaggregation of buoyant material. Some satellite images reveal submesoscale activity visually comparable to the ones simulated here. (AU)