Sack Lunch Seminar (SLS)

Assessing the Forced and Intrinsic Ocean Variability in Multi-Resolution Global DRAKKAR Simulations






The European Drakkar group is builiding and distributing an ensemble of ocean/sea-ice models and simulations at increasing resolution (2°, 1°, 1/2°, 1/4° global setups, 1/12° regional setups) over the period 1958-present. These runs are driven by different forcing functions based on atmospheric reanalyses and satellite products, i.e. either complete (i.e. including all resolved atmospheric scales) or devoid of certain scales (e.g. interannual variability). Simulations are collocated onto altimetric and hydrographic observational databases for a quantitative assessment of their realism, to quantify sensitivities to model parameters (numerics, resolution) or forcing, and for scientific research. After a short overview of DRAKKAR activities, we will describe how switching progressively from IPCC-like coarse resolutions to 1/4° resolution improves the skill of non-assimilated global models, not only their mean and turbulent flows, but also their variability at large time and space scales. We will then present in a realistic context how eddy-admitting models spontaneously generate (without direct forcing) a substantial, eddy-driven interannual variability, as predicted by more idealized studies.