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Communication incl. Poster: BibTeX citation key:  Caniauxb
Caniaux, G., Giordani, H., Wade, M., Dengler, M. & Hummels, R. 2009. The role of diapycnal mixing for simulating the eastern tropical Atlantic Ocean. Work presented at Third International AMMA Conference, July 20—24, at Ouagadougou, Burkina Faso.
Added by: roussot 2009-10-22 21:07:06
Categories: Ocean processes, Ocean-atmosphere interactions
Creators: Caniaux, Dengler, Giordani, Hummels, Wade
Publisher: African Monsoon Multidisciplinary Analyses (Ouagadougou, Burkina Faso)
Collection: Third International AMMA Conference

Number of views:  1028
Popularity index:  54.39%
Maturity index:  published

Generally, numerical models forced by surface fluxes without flux correction, or without data assimilation, and coupled models fail to reconstruct the Atlantic cold tongue and the associated seasonal Angola coastal upwelling. In these models, the cold tongue is displaced too far to the west and/or its cooling intensity is underestimated. Some models do not represent it at all. It results in too warm sea surface temperatures when compared with observations. The oceanic circulation is modified as well and in coupled models the atmospheric circulation is also affected.
This misrepresentation is exacerbated by the fact that mixed layer depths and heat contents in the eastern tropical Atlantic are particularly weak and any errors in the surface heat, salinity or movement budgets are prompt in enhancing biases. Among other factors, atmospheric forcing mechanisms associated with radiation, winds, cloud representation, humidity, or flux parameterizations are commonly pointed out.
Sensitivity tests performed with different numerical models, run during the formation of the cold tongue, suggest that diapycnal mixing is an important parameterization of turbulent mixing in the stratified thermocline. These tests support the idea that the major defaults of models in the eastern tropical Atlantic are not only due to atmospheric forcing, despite uncertainty in surface fluxes, but are also due to insufficient mixing just at the base of the (specially shallow) mixed layer depths. In-situ data collected during the AMMA/EGEE campaigns corroborate this modeling study.
Added by: roussot