John Marshall

Cecil and Ida Green Professor of Oceanography, MIT

Sea ice-ocean coupling using a rescaled vertical coordinate z*

Sea ice-ocean coupling using a rescaled vertical coordinate z*.

(Campin, Jean-Michel and Marshall, John and Ferreira, David), OCEAN MODELLING, vol. 24, no. 1-2, pp. pages, 2008.


Realistic representation of sea ice in ocean models involves the use of a non-linear free-surface, a real freshwater flux and observance of requisite conservation laws. We show here that these properties can be achieved in practice through use of a rescaled vertical coordinate “z*” in z-coordinate models that allows one to follow undulations in the free-surface under sea ice loading. In particular, the adoption of z* avoids the difficult issue of vanishing levels under thick ice. Details of the implementation within MITgcm are provided. A high resolution global ocean sea ice simulation illustrates the robustness of the z* formulation and reveals a source of oceanic variability associated with sea ice dynamics and ice-loading effects. The use of the z* coordinate allows one to achieve perfect conservation of fresh water, heat and salt, as shown in extended integration of coupled ocean sea ice atmospheric model.

doi = 10.1016/j.ocemod.2008.05.005