CoAuthors

Soumia Tajouri (LOPS/UBO, France); Florian Sevellec (LOPS/CNRS, France); Thierry Penduff (IGE/CNRS, France); Jean-Marc Molines (IGE/CNRS, France); Stéphanie Leroux (IGE/CNRS, France); Pierre Mathiot (IGE, France); Jeremie Mouginot (IGE/CNRS, France)

Satellite altimetry has revealed the sea surface signature of a wide range of processes and scales, from tides to multidecadal trends. While ocean warming and continental ice melt are the main drivers of global mean sea level changes, regional sea level variability also responds to fluctuations in salinity, ocean circulation, air-sea fluxes. Temperature has been identified as the main driver of regional sea level trends, but less attention has been paid to salinity impacts mainly because of the lack of historical in situ data. Recent improvements have been made in estimating continental freshwater discharges especially from Greenland and rivers, and in particular their interannual variability. Thus, it is now possible to investigate the impacts of fully-varying freshwater discharges on regional sea level and ocean circulation/dynamics. Realistic, fully-variable freshwater discharges data have been implemented in a global 1/4° ocean/sea-ice/icebergs general circulation model based on NEMO. Global sensitivity runs have been produced over 1980-2018 using 2 sources of freshwater runoffs: (i) solid/liquid discharges from Greenland, (ii) river runoffs. These 2 sources are independently set to climatological or fully variable forcings in successive simulations. In this presentation, we will present recent results (from the IMHOTEP OST/ST project) on Greenland freshwater discharge on regional sea level trends. We find that Greenland discharge may impact regional sea level trends in the Beaufort gyre over 1998-2011 with values larger than 10 mm/yr. We find that the halosteric contribution drives these trend differences located in the the upper 300m. Salinity budgets will be investigated to understand the sources and origin of such a freshening and whether the Greenland is directly responsible for such regional sea level changes.