The main fieldwork for TERIFIC has been completed. We have deployed 203 surface drifters which measure their position and properties at the ocean's surface once every hour. These drifters were deployed during different seasons (December 2019, March 2020, September 2020 and August-September 2021). The majority of drifters were deployed at the southwest corner of Greenland where the salty offshore water meets the fresh shelf currents, with the remaining ~25 in Davis Strait where they were in Arctic/Greenland-origin freshwater. The drifters then are carried downstream by ocean currents, tracking the fate of the fresh shelf currents and transmitting their position and surface ocean properties once every hour. We additionally deployed two autonomous underwater vehicles ('gliders') and a surface vehicle to overwinter in the Labrador Sea. The two gliders carried out their missions from December 2019 to May 2020, and again from December 2021 - June 2022, transiting the ocean while repeatedly diving to 1000m then surfacing and transmitting their data back to a basestation located in the UK. A surface vehicle collected surface meteorological data (winds and air temperature) as well as surface ocean properties (temperature, salinity and wave height), and transmitted this data back via satellite, however it was damaged during a storm and not retrieved. Datasets are being quality controlled and made open access via online repositories: the drifter data are immediately available via the Global Drifter Program website with quality-controlled data available ~6 months later. The first glider dataset is now quality-controlled and is available from an open repository; the second glider dataset will be appended to the same repository. The autonomous surface vehicle data available (before the vehicle was lost) will be submitted to the same repository.
Initial results from the drifter datasets show that the export from the shelf to open-ocean is sporadic, with wind playing a dominant role in the March deployment, and a marginal role in the other deployments. Additionally, the majority of the Davis Strait drifters remained on the Labrador shelf rather than exiting the shelf. These results were presented at international conferences and are in the process of being prepared for publication in a journal article. The glider datasets showed the expected development of convection and deep mixing layers in the wintertime (published in grey literature, awaiting final form). During the restratification period, deep submesoscale instabilities were identified (below 500m) which is unique to this region and contributed to the continuous restratification process. These small-scale lateral mixing processes were responsible for bringing both fresh and warm water into the open Labrador Sea. Continuing research is ongoing into the role of mixing and restratification during wintertime deep convection.
