Overview
An energy loan sea ice model was developed to manage the energetics of water phase changes in a consistent yet simple manner. The model, which has much in common with the one developed by Semtner (1976, Appendix) focuses on two aspects of the influence of sea ice: (1) the stabilization of ocean temp...
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| Format: | Text |
| Language: | English |
| Published: |
2000
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.689.4820 http://hycom.org/attachments/067_ice.pdf |
| Summary: | An energy loan sea ice model was developed to manage the energetics of water phase changes in a consistent yet simple manner. The model, which has much in common with the one developed by Semtner (1976, Appendix) focuses on two aspects of the influence of sea ice: (1) the stabilization of ocean temperature near the freezing point through ice formation and melting, and (2) the impact of the ice surface on ocean-atmosphere energy fluxes. Concerning the stabilization of ocean temperature, the energy loan concept of the ice model ensures that the oceanic mixed layer temperature does not drop below the freezing point (-1.8 o C) when the surface heat flux removes heat from the ocean. At each model grid point, the ocean borrows energy from an “energy bank ” to stabilize temperature at the freezing point. The energy required to maintain this temperature comes from freezing an appropriate amount of seawater. Conversely, if the surface heat flux adds heat to the ocean, the energy loan must be repaid before the ocean temperature in a grid box is permitted to rise above freezing. The influence of ice on surface fluxes is large, both by virtue of its high albedo compared to water and because an ice surface can be much colder than open water. In the present ice model, surface temperature is calculated based on the assumption that the system is energetically in a steady state; i.e., the heat flux through the ice matches the atmospheric heat flux. Specifics To illustrate this approach, the atmospheric heat flux is written as ()air i aF a T T =-, and the heat flux through the ice as ()ice w iF a T T =-, where iT, aT, and wT represents ice, air, and water temperature while a and b are proportionality factors. Given aT, wT, and a first guess of iT (the unknown in this problem), iT is modified by an amount iTD to minimize the difference between airF and iceF: ( ) (),i i a w i ia T T T b T T T+ D- =-- D which yields.a wi i aT bT |
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