전지구 해양순환 - 해빙 접합 모델 예비 결과

Abstract

Global simulation of the ocean circulation based on the HYbrid Coordinate Ocean Model (HYCOM) has been carried out with the inclusion of the simple sea ice model. The energy loan sea ice model which is provided in the HYCOM distribution 2.1.34 has been adopted. It has only the thermodynamics focussing two aspects. one is the stabilization of ocean temperature near the freezing point through ice formation and melting and the other is the impact of the ice surface on ocean-atmosphere energy fluxes. The meridional model grid size is variable from 1/3 degree in the tropics to the 1 degree in the temperate. Zonal grid size is set 1.5 degree uniformly in the south of 65 °N. From the 65 °N to the North Pole, a kind of arctic bipolar patch grid has been designed and attached to resolve both singularity at the pole and the ice formation process. A total of 30 vertical potential density layers have been applied but the half of them could be used as depth coordinate in the upper layer or the terrain following coordinate in the shelf region. After the 40 year spun up under the climatological forcing based on the COADS (Comprehensive Ocean-Atmosphere Data Set) data with the initial Levitus climatolgy, we have imposed the present forcing field estimated from the year 2000 results of a 20 century control run of the GFDL (Geophysical Fluid Dynamics Laboratory) Climate Model version 2.1. The general ocean circulation pattern seems to be quite good and well agreed with the observation. It is noteworthy that the annual cycle of the ice coverage in the arctic and antarctic has been well simulated. The horizontal ice extents, however, are much underestimated compared to the observation, which implies that too much heat flux imposed to the sea ice in this model, especially in the antarctic.