2 research outputs found
Resolving and parameterising the ocean mesoscale in earth system models
Purpose of Review. Assessment of the impact of ocean resolution in Earth System models on the mean state, variability, and
future projections and discussion of prospects for improved parameterisations to represent the ocean mesoscale.
Recent Findings. The majority of centres participating in CMIP6 employ ocean components with resolutions of about 1 degree in
their full Earth Systemmodels (eddy-parameterising models). In contrast, there are alsomodels submitted toCMIP6 (both DECK
and HighResMIP) that employ ocean components of approximately 1/4 degree and 1/10 degree (eddy-present and eddy-rich
models). Evidence to date suggests that whether the ocean mesoscale is explicitly represented or parameterised affects not only
the mean state of the ocean but also the climate variability and the future climate response, particularly in terms of the Atlantic
meridional overturning circulation (AMOC) and the Southern Ocean. Recent developments in scale-aware parameterisations of
the mesoscale are being developed and will be included in future Earth System models.
Summary. Although the choice of ocean resolution in Earth System models will always be limited by computational considerations,
for the foreseeable future, this choice is likely to affect projections of climate variability and change as well as other
aspects of the Earth System. Future Earth System models will be able to choose increased ocean resolution and/or improved
parameterisation of processes to capture physical processes with greater fidelity
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Atlantic multidecadal variability and North Atlantic jet: a multi-model view from the decadal climate prediction project
The influence of the Atlantic Multidecadal Variability (AMV) on the North Atlantic storm track and eddy–driven jet in the winter season is assessed via a coordinated analysis of idealised simulations with state-of-the-art coupled models. Data used are obtained from a multi-model ensemble of AMV± experiments conducted in the framework of the Decadal Climate Prediction Project component C. These experiments are performed by nudging the surface of the Atlantic ocean to states defined by the superimposition of observed AMV± anomalies onto the model climatology. A robust extra-tropical response is found in the form of a wave-train extending from the Pacific to the Nordic seas. In the warm phase of the AMV compared to cold phase, the Atlantic storm track is typically contracted and less extended poleward and the low-level jet is shifted towards the equator in the Eastern Atlantic. Despite some robust features, the picture of an uncertain and model-dependent response of the Atlantic jet emerges and we demonstrate a link between model bias and the character of the jet response