Warm water cells in the North Water, Northern Baffin Bay during winter

Abstract

Sea surface temperatures above the freezing point of seawater (−1.8°C) were observed in the North Water during winter and early spring. The result indicates a possibility of upwelling warm water, presumably of Atlantic origin, brought from lower depths to the surface. The warm water temperatures ranged from −1.7° to −0.1°C. The highest occurrence frequency lay in the temperature interval from −1.0° to −0.8°C. Most warm water cells were found along the Greenland coast in Smith Sound, Lady Ann Strait, and Barrow Strait. They occurred most frequently in Smith Sound, west of Cape Alexander. The highest temperatures of −0.1°C occurred, however, south of Cape Alexander. The occurrence frequency and the total area of warm water patches decreased toward spring. The predominantly northerly wind that is channeled in Smith Sound accounts for a mean ice drift of approximately 17 km d−1. This ice drift causes an ice divergence in Smith Sound and along the Greenland coast. The existence of warm water areas can be explained by the strong northerly wind resulting in a Coriolis force that induces coastal upwelling. The wind‐induced offshore transport of 3.5×105 m3 s−1 in the North Water, compensated by the upwelling of Atlantic Baffin Bay water (0°C) along the Greenland coast, will suffice to keep 10% of the North Water ice free. The combination of ice divergence and forced convection of warm water can be considered as a prime cause of the polynyas in the North Water.