News

Simon Wett and Katja Schultz set sail on the research vessel Thalassa for a 4-week expedition to the Transition Zone. The cruise is part of the CROSSROAD project, led by Damien Desbruyeres, but visiting the deployment sites of EPOC assets for acoustic download of data.

The rate of Greenland melting has been accelerating in the past 2 decades. Not only is Greenland releasing more freshwater into the oceans, it’s doing so to a greater extent each year. However, due to how the ocean circulation responds to the Earth’s rotation in high latitudes, that freshwater is mostly “trapped” on the shallow (500 m deep) shelves around Greenland, in the boundary currents circulating from east to west around the southern tip of Greenland, and cannot escape to the open ocean where convection occurs.

In the wintertime in the Labrador Sea, eastward travelling cold dry air from the Canadian Arctic archipelago and storms from northeast American encounter their first bit of ocean over the subpolar North Atlantic. Ocean sea surface temperatures in this region are warmer than the surface temperatures over land since they can’t remain below -1 degrees for long. This means that the ocean is warm relative to the atmosphere, and so gives off heat to the atmosphere which cools the surface waters. When waters become cooler, they become denser; if they get denser than the waters beneath them, they sink, mixing with deeper water. This process is called “deep convection”, and the end result is a well-mixed deep water mass. There are only a few places in the world where deep convection can occur in the open ocean (as opposed to continental shelves or marginal seas), including the Labrador Sea (between Canada and Greenland), Irminger Sea (between Greenland and Iceland).