Wind‐driven shelf/basin exchange on an Arctic shelf: The joint roles of ice cover extent and shelf‐break bathymetry

The efficiency of shelf/basin exchange (SBE) in polar regions during summer is strongly moderated by the location of the ice edge relative to underlying topography. Numerical model calculations suggest that upwelling‐favorable winds generate very little SBE so long as the ice edge remains shoreward of the shelf break, but an abrupt onset of shelf‐break upwelling takes place when the ice edge retreats beyond the shelf break. A climatology (1968–2000) of ice conditions from the Canadian Shelf of the Beaufort Sea shows large interannual variability in ice edge extent and duration of ice‐free conditions in summer. Similarly, available hydrographic data reflect a corresponding variability in water mass properties. Under scenarios of climate warming associated with greenhouse gas build‐up, both the extent and duration of summer melt‐back are predicted to increase, and this may have dramatic impacts on SBE and biological productivity.