Diagnoses of an Eddy-Resolving Atlantic Ocean Model Simulation in the Vicinity of the Gulf Stream. Part II: Eddy Potential Enstrophy and Eddy Potential Vorticity Fluxes

Abstract

Abstract Output of an eddy-resolving model of the North Atlantic is diagnosed in the vicinity of the Gulf Stream (GS), using quasigeostrophic potential vorticity (QGPV), quasigeostrophic potential enstrophy (QGPE), and modified divergent eddy potential vorticity flux, (V′hq′*)d. A tongue or an elongated island of large mean QGPV along the model GS in the top 1000 m is associated with predominantly downgradient (V′hq′*)d, suggesting that the horizontal eddy fluxes are balancing a sink of eddy QGPE in most of the tongue or island by converting the mean QGPE into eddy QGPE. Some large upgradient (V′hq′*)d is observed to the north of the center of the tongue or island, however, suggesting that some of the eddy fluxes in the northern half of the tongue or island of high QGPV are balancing a source of eddy QGPE there by converting eddy QGPE into the mean QGPE. At the intermediate levels of the model, under the GS, eddy QGPE is small, and the role of eddies appears to be mixed; they are forcing the mean to some ...