Wind-driven transport of fresh shelf water into the upper 30 m of the Labrador Sea

Lena M. Schulze Chretien, Eleanor Frajka-Williams
2018 Ocean Science (OS)  
<p><strong>Abstract.</strong> The Labrador Sea is one of a small number of deep convection sites in the North Atlantic that contribute to the meridional overturning circulation. Buoyancy is lost from surface waters during winter, allowing the formation of dense deep water. During the last few decades, mass loss from the Greenland ice sheet has accelerated, releasing freshwater into the high-latitude North Atlantic. This and the enhanced Arctic freshwater export in recent years have the
more » ... s have the potential to add buoyancy to surface waters, slowing or suppressing convection in the Labrador Sea. However, the impact of freshwater on convection is dependent on whether or not it can escape the shallow, topographically trapped boundary currents encircling the Labrador Sea. Previous studies have estimated the transport of freshwater into the central Labrador Sea by focusing on the role of eddies. Here, we use a Lagrangian approach by tracking particles in a global, eddy-permitting (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M1" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">1</mn><mo>/</mo><mn mathvariant="normal">12</mn><msup><mi/><mo>∘</mo></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="31pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="31f94f69d3140785962714142bd04d66"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="os-14-1247-2018-ie00001.svg" width="31pt" height="14pt" src="os-14-1247-2018-ie00001.png"/></svg:svg></span></span>) ocean model to examine where and when freshwater in the surface 30<span class="thinspace"></span>m enters the Labrador Sea basin. We find that 60<span class="thinspace"></span>% of the total freshwater in the top 100<span class="thinspace"></span>m enters the basin in the top 30<span class="thinspace"></span>m along the eastern side. The year-to-year variability in freshwater transport from the shelves to the central Labrador Sea, as found by the model trajectories in the top 30<span class="thinspace"></span>m, is dominated by wind-driven Ekman transport rather than eddies transporting freshwater into the basin along the northeast.</p>
doi:10.5194/os-14-1247-2018 fatcat:3d4xrbgkmfazhb5oesfle5q424