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Study Finds Small-Scale Flows Alter Transport Pathways on the Ocean’s Surface

September 5, 2017
Scientists analyzed model simulations of tracer dispersion in a Gulf of Mexico eddy to find out if small-scale flows surrounding the eddy influenced where the tracer went. The researchers observed that the small-scale flows disrupted the eddy’s large-scale flow patterns enough so that 20-50% of the tracer that was entrained in the eddy leaked out, crossed into surrounding areas, and followed flows of nearby eddies. The researchers published their findings in Ocean Modelling: Impact of submesoscales on surface material distribution in a Gulf of Mexico mesoscale eddy.

Understanding particle movement at the ocean’s surface is important for several applications, one being the tracking of buoyant pollutants such as oil spills that require rapid forecasts to reduce environmental and socioeconomic damage. However, this is a challenge because of highly variable surface currents, and wide-ranging spatial scales on the ocean’s surface.

Ocean circulation models can reproduce the meso or large-scale (greater than 10s of km, lasting days to months) circulation features using the assimilation of satellite altimetry data. However, submesoscale (100 m to 10 km scales, lasting hours to a day) circulation features have different dynamics and little is known about how they interact with mesoscale circulations and affect transport of buoyant tracers. This study’s authors used the Hybrid Coordinate Ocean Model to simulate an eddy that exhibited bursts of small-scale flows along its rim and applied filters to isolate the mesoscale from the submesoscale features. The researchers compared the entrainment of a tracer by the eddy with and without submesoscale features and then analyzed its dispersion properties on the ocean’s surface.

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