Mean climate state simulated by a coupled ocean-atmosphere general circulation model

Summary The result of a 100-year integration of a coupled ocean-atmosphere general circulation model (CGCM) is analyzed, and compared with that of a 25-year integration of the corresponding uncoupled atmospheric general circulation model (AGCM) and observed data. The large-scale circulation patterns of mean climate state simulated by the CGCM are in good agreement with the observed ones, although differences exit in the positions and intensities between the simulated and the observed patterns. Having compared the standard deviations of monthly mean sea level pressure simulated by the CGCM to those by the AGCM, we found that the interaction between ocean and atmosphere mainly increases the interannual variability in the tropics especially in summer. The CGCM can also produce El Niño and Southern Oscillation (ENSO) events, whereas the AGCM cannot reproduce the main features of the Southern Oscillation. This implies that the air-sea interaction may be a principal mechanism for the occurrence of ENSO phenomena. The fundamental features of simulated regional climates are also analyzed. The CGCM can reproduce principal characteristics of surface air temperature and precipitation at five selected typical regions (desert region, plain region, monsoon region etc.). The distributions of annual mean surface ait temperature and precipitation in East Asia can also be reasonably simulated.With 9 Figures