Oceanographic features in the Newfoundland marginal ice zone, March‐April 1990

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Abstract
Temperature, salinity and ice drift data collected in the Newfoundland marginal ice zone during the period of ice retreat in 1990 are analysed to identify oceanographic features that are important for studies of sea‐ice distribution and movement. The cold and low‐salinity shelf water covered with sea ice is found eastward of the shelf break in the upper 100 m of the water column. A sharp surface temperature/salinity front separates this water from the warmer and more saline waters of the Labrador Sea. The presence of the shelf water in the deep water region can be attributed to the effects of wind forcing, ice melting and frontal instability. Associated with the front is a southward flowing current of 0.24 ms−1. Evidence of this frontal jet is found from both the ice drift data and dynamic calculations. The Labrador Current is locked to the topography. Its position and velocity are not affected by the presence of the sea ice. At the ice edge, intense mixing manifested by an interleaving structure of the temperature field is frequently observed. Sea‐ice distribution and motion can be strongly affected by these oceanographic features, and in turn, sea ice can play an important role in creating these features. The observations suggest that in studying the marginal ice zone, coupled ice‐ocean dynamics and thermodynamics should always be considered.