Abstract's details

Contribution of Time-varying Discharge from Greenland and Rivers to Regional Sea Level Change in the Arctic Ocean

Soumaia Tajouri (LOPS - UBO/CNRS/IFREMER/IRD, France)


William Llovel (LOPS - CNRS/IFREMER/IRD/UBO, France); Florian Sévellec (LOPS - CNRS/IFREMER/IRD/UBO, France); Thierry Penduff (Institut des Géosciences de l’Environnement, Grenoble, France); Jean-Marc Molines (Institut des Géosciences de l’Environnement, Grenoble, France); Stéphanie Leroux (Institut des Géosciences de l’Environnement, Grenoble, France)

Event: 2023 Ocean Surface Topography Science Team Meeting

Session: Science I: Understanding and Quantifying Regional and Global Sea Level Budgets

Presentation type: Type Forum only

Contribution: PDF file


Global mean sea level rise is an important indicator of ongoing climate change. For the first time, high-quality satellite altimetry data reveal large regional variability in sea level trends with regions experiencing a linear rise three times larger than the global mean trend. These trends are mainly explained by temperature changes. However, salinity changes can also play an important role in several regions such as in the Arctic Ocean. These temperature/salinity changes are themselves linked to a variety of drivers such as ocean circulation, ocean dynamics, air-sea fluxes and continental freshwater discharges. In particular, freshwater discharges from Greenland and rivers remain poorly understood due to a lack of in situ measurements. Recent improvements in the estimation of the interannual variability of freshwater discharges from Greenland and rivers allow us to isolate and quantify the contribution of such freshwater discharge to regional sea level change over the altimetric period 1993-2018.

For that purpose, we make use of sensitivity experiments based on NEMO 1/4° global ocean/sea-ice/icebergs forced runs integrated over 1980-2018 where Greenland and rivers discharge are successively set to climatological and fully variable. This reveals the individual and cumulative impacts of these freshwater sources on regional sea level change.

We find that Greenland and rivers variability produce an opposite impact on regional sea level trends in the Beaufort Gyre Region (BGR), the former driving an increase, while the latter, a decrease. Their combined impact leads to fairly no sea level trend in that region. The sea level response is primarily driven by salinity variations in the 300 m upper meters, themselves mainly due to convergence of salinity anomalies by the ocean circulation. Our results indicate that local sea ice melt does not play a major role in the freshwater budget of the BGR.

This study gives support to account for the full variability of continental freshwater discharge in forced models in order to better represent regional sea level variability. As Greenland might impact regions far away from its coasts in the Arctic Ocean, being able to simulate Greenland consequences correctly is important for the understanding of the current and future Arctic climate changes.
Soumaia Tajouri