Development of a simple oceanic mixed-layer and sea-ice model for use with an atmospheric GCM. Volume 1
A simple numerical model of the oceanic mixed layer and sea ice is described which is suitable for coupling to an atmospheric GCM. Earlier models of the mixed layers and sea ice as separate components are combined with little modification. Sea-ice thickness is determined thermodynamically by local melting or accretion, and the effects of ice transport and leads are neglected. Three model versions for the mixed layer are considered, ranging from a water slab of fixed thickness to a variable-depth mixed layer above the variable exponential temperature profile representing the seasonal thermocline. The model is tested by integrating to equilibrium in a zonally symmetric mode, using monthly climatological atmospheric data for a seleted north-south section in the mid-Pacific ocean, and the results for different model versions are compared with each other and with available observations. It is found that the fixed-slab version gives realistic sea-ice thickness and extent, and temperatures within approx.1 to 2/sup 0/C of observed sea-surface temperatures over much of the mid-Pacific. However, a variable-depth mixed layer is required to maintain this level of accuracy for summer sea-surface temperatures north of 40/sup 0/N, and also to produce the correct phases of the annual cycles of temperature at all extratropical latitudes. Mixed-layer depths in the latter version are somewhat too shallow in winter, but overall seasonal pattern agrees with that observed. It is found that the addition of north-south advection by mixed-layer currents can give a reasonable simulation of equatorial upwelling. The use of different model versions results in different amounts of net annual vertical heat exchange with the deep ocean, which may be a significant effect for some climatic experiments with a coupled atmospheric GCM. 53 refs., 10 figs.
- Research Organization:
- Oregon State Univ., Corvallis (USA)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5447521
- Report Number(s):
- UCRL-15704-Vol.1; ON: DE85017264
- Resource Relation:
- Other Information: Climatic Research Institute Report No. 21
- Country of Publication:
- United States
- Language:
- English
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