We recently applied
CANDIE to the northwest Atlantic Ocean forced by monthly mean COADS surface wind stress and heat flux, and flows through the model open boundaries. The model salinity at the sea surface, and the temperature and salinity along the open boundaries, are restored to the monthly mean climatology with a time scale of 15 days. The flow across the open boundaries is taken to be the combination of a baroclinic component determined from density using thermal wind, and a barotropic component determined from the large-scale diagnostic calculation for the whole North Atlantic produced by Greatbatch et al. [1991]. To improve the predictive skill of the model, we proposed a semi-prognostic method by adjusting the model predicted currents toward climatology, while leaving the model temperature and salinity equations unconstrained. The adjustment is accomplished by replacing the density term in the hydrostatic equation with a linear combination of model-predicted and climatological density. The model results produced using this method show a significant improvement over those produced by either pure diagnostic or pure prognostic model runs. The proposed method reproduces many well-known circulation features in the region, including the Labrador Current, the Gulf Stream and the North Atlantic Current. More significantly, the method reproduces reasonably well the seasonal evolution of temperature and salinity in the region, despite the fact the model temperature and salinity equations are not constrained by the assimilation procedure.

For details, please click here to download the ps-file of the paper.

Animation of the Seasonal Circulation in the Northwest Atlantic Ocean

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