Dinniman¹, Michael S., John M. Klinck¹, Walker O. Smith, Jr. ² and Eileen E. Hofmann¹

¹Center for Coastal Physical Oceanography, Old Dominion University, Crittenton Hall, Norfolk, VA 23529, Phone: 757-683-5559, Fax: 757-683-5550, E-mail: msd@ccpo.odu.edu and ²Virginia, Institute of Marine Science, College of William and Mary

Cross shelf exchange in the Ross Sea and west Antarctic Peninsula from models of the circulation and biogeochemistry

Exchange of warm, nutrient-rich Circumpolar Deep Water (CDW) onto Antarctic continental shelves and coastal seas has important effects on physical and biological processes. This water mass moderates the ice cover through heat flux, provides a relatively warm subsurface environment for some animals and provides nutrients to stimulate primary production. CDW exchange is known to be episodic, but persistent, and is thought to occur at specific locations due to bottom topography. The present study, using a high-resolution three-dimensional numerical model, investigates the locations of this exchange and their dynamics in the Ross Sea and west Antarctic Peninsula.

Calculations of the advective transport across the shelf break and budgets on the shelf of heat, salt and nutrients show that the cross shelf break transport of CDW is very important to the total budgets on both shelves. There is a significant correlation between the horizontal curvature of the shelf break and the transport across the shelf break. A term balance for momentum shows that momentum advection forces flow across the shelf break in specific locations due to the curvature of the bathymetry (that is, the isobaths curve in front of the flow). For the model to create a strong intrusion of CDW onto the shelf, two mechanisms are necessary. First, CDW is driven onto the shelf at least partially by momentum advection and the curvature of the shelf break; then, the general circulation on the shelf takes the CDW into the interior.