Abstract
Submesoscale eddies play an important role in the energy transfer from the mesoscale down to the dissipative range, as well as in tracer transport. They carry inorganic matter, nutrients and biomass; in addition, they may act as pollutant conveyors. However, synoptic observations of these features need high resolution sampling, in both time and space, making their identification challenging. Therefore, HF coastal radar were and are successfully used to accurately identify, track and describe them. In this paper we tested two already existing algorithms for the automated detection of submesoscale eddies. We applied these algorithms to HF radar velocity fields measured by a network of three radar systems operating in the Gulf of Naples. Both methods showed shortcomings, due to the high non-geostrophy of the observed currents. For this reason we developed a third, novel algorithm that proved to be able to detect highly asymmetrical eddies, often not properly identified by the previous ones. We used the results of the application of this algorithm to estimate the eddy boundary profiles and the eddy spatial distribution.
Highlights
Transport in the ocean develops over an extremely wide range of scales, from the basin to the dissipation scale (e.g., [1])
We note that in both algorithms AMEDA and Nencioli et al algorithm’ (NEAL) the final step concerns the rotation of the velocity vector along a boundary profile
This was explicitly done by following the path counter-clockwise and verifying that any velocity vector at a given grid point was rotated to the left of the previous by an angle less than π/2 radians; note that this criterion does not depend on the sense of rotation of the velocity field along the path
Summary
Transport in the ocean develops over an extremely wide range of scales, from the basin to the dissipation scale (e.g., [1]). Submesoscale eddies principally act as energy conveyors from the mesoscale to the microscale, and play a crucial ecological role: they may influence the state of health of ocean regions through their ability to carry heat, inorganic matter, nutrients and biomass ([4,5]), ensuring the connectivity between different ecosystems ([6]). They are important for phytoplankton, as they develop over timescales similar to those of phytoplankton growth ([7]), they may act as carriers of pollutants (see, e.g., [8]). The detection of eddies, behind its inherent interest, is crucial for environmental applications
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