Effects of physical processes of H₂O on the general circulation of the atmosphere; part II

In Part 1 (Miyoshi and Morita, 1993), we investigated how the general circulation of the atmosphere was affected by all the physical processes of H₂O. In this study, we divide all the physical processes of H₂O into the radiative process of H₂O and the hydrological cycle, and investigate the effect of both of the processes separately by a series of GCM experiments. Results are as follows. The north-to-south temperature gradient and the zonal wind distribution below 5 km height is strongly affected by the radiative process of H₂O. The strength of the meridional circulation, the magnitude of the poleward energy transport, the magnitude of the sensible and latent heat fluxes and the magnitude of the diabatic heating rate in the atmosphere also depend on the radiative process of H₂O. Thus, the differences of the general circulation between with and without all the physical processes of H₂O is mostly caused by the radiative process of H₂O. The zonal wind distributions above 5 km height, on the other hand, are affected by not only the radiative process of H₂O but also by the hydrological cycle. Numerical experiments using a vertically one-dimensional radiative-convective equilibrium model are performed. By comparing the radiative-convective equilibrium temperature with the temperature in the GCM, the relation between the poleward heat transport by the dynamics and the physical processes of H₂O is also examined. In the experiments without the radiative process of H₂O, the temperature near the surface in the GCM is almost the same as the radiative-convective temperature. At low latitudes, the temperature difference between the GCM and the radiative-convective model is larger in the experiments with the radiative process of H₂O than in the experiments without the radiative process of H₂O.