Eddies and finestructure variability in the NAC

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Observational estimates of elevated vertical diffusivity in regions of high mesoscale eddy activity point toward the relevance of energy loss from eddies to maintain the ocean stratification. Estimates of net energy transfers between the internal wave field and a mesoscale eddy field indicate wave–eddy coupling as an important source of internal wave energy, and thus mixing, in the deep ocean. Here it is proposed to investigate the relation of eddies in two energetic regions, the North Atlantic Current (NAC) and the Antarctic Circumpolar Current (ACC), to finescale variability of the internal wave field observed in vertical profiles of density and velocity. The study has the major objectives to find relations between finescale variance and external properties of the mesoscale flow estimated from satellite and shipboard observations, and to examine the role of topographyflow interaction for the spatial distribution of finescale variance. The results from the NAC will be compared to the estimates from the ACC, where additionally the long-term variability of finescale variance in relation to the wind stress strengthening in the region of the ACC will be investigated.