A study of the effects of different parameterizations of the surface fluxes on stability of the climate system using a simple box model

摘要

Recently it has been proposed (in a simple model study of the surface fluxes) that there is a robust mechanism linking the surface temperature and the surface wind via atmospheric angular momentum transport. The analysis of the simple model suggested that the proposed mechanism can enhance the stabilizing effect of evaporation on the surface temperature. This issue is studied here using a simple two zone hemispheric model of the atmosphere-ocean system. We relax the two critical assumptions from the above-mentioned study, namely the assumption of a constant air-sea temperature difference and constant near-surface relative humidity, respectively. It is found from the stability analysis of the model that the proposed coupling of the surface wind to the sea surface temperature together with the Clausius-Clapeyron effect of the evaporation always increases the stability of the system as is seen in the earlier studies, but the extent to which it does is diminished by new feedbacks created by the relaxed assumptions. It is also seen that this main stabilizing effect of the surface energy budget, which is related to dynamics, has a different counterpart when looking at the top of the atmosphere energy budget which is related to the radiation. Finally, it is seen that, depending on the assumptions made, quite different physics are becoming responsible for the stability of the surface temperature.