The simulations of the Arctic ice-ocean circulation using the high resolution global coupled atmosphere-ice-ocean model with 1/6x1/4 degrees and 48 vertical layers on the ‘Earth Simulator’ supercomputer was evaluated to determine the model performance, physics soundness, and its sensitivity to different process parameterizations. The model was parameterized by GM (Gent McWilliams 1990) parameterization to the north of 45N. The statistical time series of the total oceanic and ice kinetic energy and ice areas suggest that there is an equilibrium without any T/S restoring or flux adjustment, and no model drifting is found. The model climatology (mean over all the model years) and variability were examined and compared with the available observations, such as ice area, temperature and salinity at certain key depths and transects. Several important physical features in the Northern Hemisphere, such as the thermohaline in the Arctic Ocean, Atlantic Water, meridional thermohaline overturning, transports from Bering Strait, Fram Strait etc., were examined to determine physical soundness of the model. An important achievement is that the Atlantic Layer in the Arctic can be reasonably reproduced with no restoring temperature and salinity to observations. An important criterion of reproducing the Atlantic Layer variability is measured by the core (max) temperature of the layer of 500-1500m. The model produces reasonably the 20th century Atlantic Water core temperature that compares well with observation by Polyakov et al. (2004). The model catches the 1930s-40s warming and the 1990s warming, similar to the observation. These results indicate that this coupled global model captures most important dynamic and thermodynamic processes in the Arctic Ocean. Further analysis of the model performance is under way.

References:

Wang, J., M. Jin, J. Takahashi, T. Suzuki, J.E. Walsh, H. Hasumi and I.V. Polyakov, 2006. Modeling Arctic Ocean warming episodes in the 20th century caused by the intruding Atlantic Water. (submitted to Geophys. Res. Lett.)

Wang, J., M. Jin, J. Takahashi, T. Suzuki, J.E. Walsh, H. Hasumi and M. Ikeda. Multi- decadal variability of the Arctic Atlantic Water during the 20th century: Modeling vs. observations. (in prep)