The AMOC and subpolar gyre circulation at the OSNAP section in summer 2014

The overturning and gyre circulation in the subpolar North Atlantic is being measured by the international observing array deployed by OSNAP (Overturning in the Subpolar North Atlantic Programme, www.o-snap.org). The OSNAP line crosses the Labrador Sea from 52N to the southern end of Greenland, and lies across the Irminger Sea, Iceland Basin and Rockall Trough at approximately 60-57°N. The array, deployed 2014-2018, uses moored instruments, gliders and floats to measure the surface to seafloor circulation. OSNAP is novel and exciting because it is making the first ever continuous measurements of the Atlantic Meridional Overturning Circulation in the subpolar region. In time, OSNAP will generate products analogous to the RAPID time series at 26N.

In this study we use a high resolution CTD/LADCP OSNAP section from summer 2014 to provide a synoptic view of the circulation, heat and freshwater fluxes at the time that the array was deployed. The data represent the first time that the entire subpolar region including the Labrador Sea has been measured in a single cruise (GO-SHIP section AR07, cruise JR302). We will present estimates of both the horizontal and overturning circulation, and the latter will be examined both in pressure and in density co-ordinates. We will show volume, heat and freshwater transports for the whole section and key components, including the deep boundary currents and shallow shelf currents containing freshwater exported from the Arctic.