Tidal Effects on the Lead Fraction and the associated Ocean-Atmosphere Heat Flux in the Weddell and Ross Seas

Columbia University, New York NY

Investigators

Abstract

This project will examine the characteristics and effects of tides in the Weddell and Ross Seas, using a three-dimensional free surface coupled sea ice/ocean model to study the barotropic and baroclinic components of the tide and their effects on the structure of sea ice. Antarctic sea ice and tides are important factors affecting the air-sea heat flux, deep water formation, dynamics, and mixing in high southern latitudes. At the present time, tidal processes and their effects have generally not been included in wind-driven coupled ice-ocean models and sea ice has been ignored in the tidal models of the Antarctic Seas. In this study a terrain-following coordinate model, modified to include the ice shelves, is combined with a granular rheology sea ice model and will be used to generate 45-day scenarios, one for each season, based on climatological forcing. Simulations will be made both without and with tidal forcing in order to quantify the tidal effects during the different sea ice, mixed layer, and wind conditions associated with each season. Climatological seasonal atmospheric conditions with realistic daily variability for the forcing will be provided by the European Centre for Medium-Range Weather Forecasts. The investigation will include tidal effects on 1) formation of open water, 2) the ocean-atmosphere heat flux, 3) the mean ocean circulation, 4) shelf water formation due to brine rejection, 5) mid-water column mixing due to shear instabilities, and 6) benthic mixing. Both Antarctic Bottom Water and Ice Shelf Water production will be determined from the model results.