ANNUAL MEAN MERIDIONAL ENERGY-TRANSPORT MODELED BY A GENERAL-CIRCULATION MODEL FOR PRESENT AND 2-X-CO2 EQUILIBRIUM CLIMATES

The meridional energy flux modelled by the Bureau of Meteorology Resea rch Centre general circulation model is examined. It is divided into a tmospheric and oceanic components, and the resolved atmospheric compon ents in turn into mean and eddy circulations. Comparison with observat ions shows the modelled total planetary meridional energy transport to be low, but shows better agreement for the resolved atmospheric compo nent alone. The overall patterns of the individual circulation and ene rgy components of the model also agree well, although strengths and lo cations do show some discrepancies. The doubled CO2 climate change is analyzed in terms of the changes in each of the circulation and energy components. It is found that the changes are the relatively small res idual of larger, and generally opposing changes in sensible heat and p otential energy fluxes. Despite the general decrease in poleward energ y flux, the poleward latent heat flux is found to increase. The reduct ion in poleward transport is found to be dominated by changes in the m ean meridional circulation at low southern latitudes, and changes in b oth mean circulations and eddy fluxes elsewhere.