2006 Annual Meeting and Arctic Forum | Abstracts

Simulating the 20th Century Arctic Sea Ice and Ocean Circulation Variability Using a Global Coupled Atmosphere-Ice-Ocean Model

Jia Wang¹, Meibing Jin², Jun Takahashi³, Tatsuo Suzuki⁴, John E. Walsh⁵, Hiroyasu Hasumi^6
1International Arctic Research Center, University of Alaska Fairbanks, 930 Koyukuk Drive, Fairbanks, AK, 99775, USA, Phone 907-474-2685, Fax 907-474-2643, jwang@iarc.uaf.edu
²International Arctic Research Center, University of Alaska Fairbanks, PO Box 757340, Fairbanks, AK, 99775-7340, USA, Phone 907-474-2442, Fax 907-474-2643, mjin@iarc.uaf.edu
³International Arctic Research Center, University of Alaska Fairbanks, PO Box 757335, Fairbanks, AK, 99775-7335, USA, Phone 907-474-1959, Fax 907-474-2643, jt@iarc.uaf.edu
⁴Frontier Research Center for Global Change, Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan
⁵International Arctic Research Center, University of Alaska Fairbanks, PO Box 757340, Fairbanks, AK, 99775-7340, USA, Phone 907-474-2677, Fax 907-474-2643, jwalsh@iarc.uaf.edu
⁶Center for Climate System Research, University of Tokyo, Kashiwa, Japan, hasumi@ccsr.u-tokyo.ac.jp

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 are 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 the model reaches 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 structure in the Arctic Ocean, Atlantic Water, meridional 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 reproduces reasonably the Atlantic Water core temperature in the 20th century that compares well with the observation by Polyakov et al. (2004). The model catches the 1930s-40s warming and the 1990s warming, similar to the observations. These results indicate that this coupled global model captures most important dynamic and thermodynamic processes in the Arctic Ocean. Further analyses of the model performance is underway.