Near real-time tracking of freshwater escaping the shelf west of Greenland

Ilona Goszczko and Eleanor Frajka-Williams, National Oceanography Centre, Southampton, United Kingdom
Freshwater west of Greenland is comprised of Arctic outflow, ice sheet melt and precipitation. In summer 2019, Greenland lost a great amount of ice which was in part associated with summer atmospheric heatwaves that increased glacial melting and in consequence strengthened the upper ocean stratification. During that time, unusual easterly winds increased melt on the west side of the island. In addition, the minimum of the Arctic Ocean’s sea ice extent in late summer 2019 (4.3 million km2) was below the 2011-2018 average but still above (~0.9 million km2) the record minimum in mid-September 2012.

In the TERIFIC project, we will study the pathways of freshwater escaping from the west Greenland shelf as well as deep convection and restratification in the Labrador Sea. Strikingly, deep convection re-appeared in 2014, exceeding 1500-2000m in 2016, in spite of intensified global climate warming and concurrent freshwater surplus.

To tackle this chain of atmosphere-ice-ocean processes we will use various instrumentation during our fieldwork: 1) surface drifters deployed south-west of Greenland (~60°N) capturing pathways of freshwater along the shelf break (coastal current) and across the shelf (e.g., surface Ekman transport and current instabilities); 2) ocean gliders measuring the Labrador Sea temperature and salinity from the surface down to 1000m; 3) an autonomous Sailbuoy surveying the convection sites in winter and measuring atmospheric conditions; 4) CTD profiles collected on the shelf and inside the Greenland fjords compared against historical hydrographic data. Here we will present the initial results from the first field campaign in December 2019, and place these in the historical context where data are available and with reference to atmospheric indices and measures of freshwater release from the Arctic and Greenland.