Mesoscale and submesoscale effects on mixed layer depth in the southern ocean

In this paper, a series of offline-nested numerical simulations is used to study submesoscale flow in theDrake Passage and Scotia Sea regions of the Southern Ocean. These simulations are initialized from an ocean state estimate for late April 2015, with the intent to simulate features observed during the Surface Mixed Layer at Submesoscales (SMILES) research cruise, which occurred at that time and location.

The nested models are downscaled from the original state estimate resolution of 1/12 degrees and grid spacing of about 8 km, culminating in a submesoscale-resolving model with a resolution of 1/192 degrees and grid spacing of about 500m. The submesoscale eddy field is found to be highly spatially variable, with pronounced hot spots of submesoscale activity. These areas of high submesoscale activity correspond to a significant difference in the 30-day average mixed layer depth DHML between the 1/12 degrees and 1/192 degrees simulations.