An overview of physical processes in the North Water

The presence of a polynya strongly affects biological processes by influencing underwater light levels, water-column stratification, the upwelling of nutrients, and the timing of production cycles. An overview of the existing literature on the oceanography, meteorology and sea-ice conditions of the North Water, a large recurring polynya in northern Baffin Bay, is presented. The North Water is influenced by a cold inflow of Arctic Ocean water from the north and, in some areas, a warmer inflow of Atlantic water from the south. Earlier observations and modeling studies suggested that both wind and ocean advection of sea ice, as well as heat input to the surface waters by either upwelling or mixing, were responsible for the formation and maintenance of the polynya. Recent data indicate the North Water to be primarily generated by the southward drift of ice by winds and currents, as opposed to melting ice by sensible heat input over large areas. Localized sensible heat effects occur in fall, winter and spring along the Greenland side of the polynya.