Publication Date:
2023-08-08
Description:
〈jats:p〉Abstract. The ocean mixed layer is the interface between the ocean interior and the atmosphere or sea ice and plays a key role in climate variability. It is
thus critical that numerical models used in climate studies are capable of a good representation of the mixed layer, especially its depth. Here we
evaluate the mixed-layer depth (MLD) in six pairs of non-eddying (1∘ grid spacing) and eddy-rich (up to 1/16∘) models from the
Ocean Model Intercomparison Project (OMIP), forced by a common atmospheric state. For model evaluation, we use an updated MLD dataset computed from
observations using the OMIP protocol (a constant density threshold). In winter, low-resolution models exhibit large biases in the deep-water
formation regions. These biases are reduced in eddy-rich models but not uniformly across models and regions. The improvement is most noticeable in
the mode-water formation regions of the Northern Hemisphere. Results in the Southern Ocean are more contrasted, with biases of either sign remaining
at high resolution. In eddy-rich models, mesoscale eddies control the spatial variability in MLD in winter. Contrary to a hypothesis that the
deepening of the mixed layer in anticyclones would make the MLD larger globally, eddy-rich models tend to have a shallower mixed layer at most
latitudes than coarser models do. In addition, our study highlights the sensitivity of the MLD computation to the choice of a reference level and
the spatio-temporal sampling, which motivates new recommendations for MLD computation in future model intercomparison projects.
〈/jats:p〉
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
Format:
application/pdf
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