[A-CG46] Science in the Arctic Region

[ACG46-P05] Multidecadal trends of sea ice melt in the Labrador Sea/Baffin Bay revealed by T-S observations

*Vigan Mensah¹, Miho Ikeda², Mizuki Komatsu¹, Kay I. Ohshima^1,3 (1.Institute of Low Temperature Science, Hokkaido University, 2.Department of Earth and Planetary Science, Faculty of Science, Hokkaido University, 3.Arctic Research Center, Hokkaido University)

Keywords:Sea ice melt, Arctic Ocean, Climate change

The Labrador Sea plays an important role in the Atlantic Meridional Ocean Circulation (AMOC) as it provides waters that become a part of the North Atlantic Deep Water, one of the main components of AMOC. The Labrador Sea is connected to the north to Baffin Bay, which is itself connected to the fresher Beaufort Sea via the Nares Strait. The hydrography of the Labrador Sea and Baffin Bay is strongly influenced by the cycle of sea ice production, drift and melt. These areas have likely been affected by the long-term changes in seasonal sea ice production as well as the increasing trend in multi-year ice and glacier ice melting. Satellite-derived sea ice thickness data only provides a record of ~20 years, and direct observations of sea ice thickness are usually scarce in both space and time. In this study, we used historical data of ocean temperature and salinity from 1950 to 2020 to estimate sea ice melt and establish meltwater thickness climatologies and time series, allowing us to document the multidecadal variability of ice melt in the Labrador Sea and Baffin Bay. Climatologies for the periods before and after 2003 reveal a clear decline in meltwater thickness between 45°N and 62°N, which we attribute to the decrease in seasonal sea ice production from the southern Baffin Bay to the Labrador Sea. A clear decreasing trend in ice melt is also visible in the time series, with a decrease in meltwater thickness of 6.2 cm per decade since 1970. In contrast, northern Baffin Bay exhibits a large increase in meltwater thickness, which might be caused by the melting and subsequent southward transport of multi-year ice from the Beaufort Sea. Another possible cause could be the transport of increasing amounts of meltwater from the east Greenland glaciers via the local coastal currents.