GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel
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22.11.2021: Ocean Circulation and Climate Dynamics Colloquium
Dr. Rene van Westen: "High-resolution Modelling of Sea-level Projections - A Necessity or a Luxury Problem?"
When? Monday, 22. November 2021 at 11 am
Where? ZOOM meeting room: https://geomar-de.zoom.us/j/84678095758?pwd=b2t2Rk5BbzhwMzNlZzJwM3p4WDBQUT09
Meeting-ID: 846 7809 5758
Kenncode: 264250
Abstract:
Satellite-observed sea-level measurements indicate an ongoing increase of the global mean sea level since the satellite era. Global mean sea-level rise threatens low-lying coastal regions and these regions will strongly benefit from accurate sea-level projections to adapt their coastal protection infrastructure. Current sea-level projections are based on climate models in which ocean-eddy processes are parameterised. In these climate models, sea-level variability and the present-day climate state strongly deviate from available observational records. These model related deficiencies may affect sea-level projections and it is therefore interesting to investigate the effect of the model resolution on sea-level projections.
Here we will investigate the effect of ocean model resolution on sea-level variability and sea-level projections. We analyse a version of the Community Earth System Model (CESM) in which ocean-eddy processes and interactions are explicitly resolved by the model. The results of the eddying version of the model are compared to a non-eddying version of the same model. First, we will briefly analyse the sub-annual variability in both versions of the model and compare the results with available observations. Next, we force both models under an idealised forcing scenario (1% CO 2 ) for 100 years. In the forcing experiment, we investigate regional (Caribbean) and global mean sea-level projections, together with an analysis and comparison of CMIP6 models (under the same forcing scenario). The results indicate that realistic sea-level projections can only be obtained by using ocean-eddying models. Relatively small-scale ocean eddies can hence have profound large-scale effects and consequently affect global mean sea-level projections.
