Modeling Wind-Driven Circulation and Landfast Ice-Edge Processes during Polynya Events in Northern Baffin Bay

Abstract

AbstractA high-resolution sea ice–ocean numerical model of the North Water polynya has been developed to study the wind-driven circulation during polynya events. An idealized three-layer stratified ocean is used to initialize the model to characterize the baroclinic response to realistic wind and ice conditions. The model general circulation pattern is mainly forced by an along-channel sea level gradient between the Arctic Ocean and Baffin Bay, which determines the magnitude of the southward Baffin Current, and by an across-channel sea level gradient in Baffin Bay, which drives the northward West Greenland Current (WGC). These two currents are found to be anticorrelated to each other in the Smith Sound area. During strong northerly wind events, occurring quite frequently in the winter–spring period in the polynya, nutrient-rich Baffin Bay waters transported by the WGC are forced toward the Greenland shelf, coinciding with upwelling events along the Greenland coast. Whenever an ice bridge is present (i.e., the polynya exists and is substantially open), upwelling also occurs at the landfast ice edge. In such cases, the total upwelling area is increased by an amount that depends on the form of the ice bridge but could easily double during certain years. The baroclinic circulation associated with the upwelling response includes the formation of a cyclonic eddy attached to the ice edge that is generated during strong northerly wind events. Primary production estimations reveal that upwelling during polynya events plays a significant role in the early spring phytoplankton bloom, suggesting that the disappearance of the polynya as a result of climate change may have profound implications for the entire ecosystem.