Abstract

This study analyzes simulation of the Subantarctic Mode Water (SAMW) and Antarctic Intermediate Water (AAIW) in eight coupled climate models (GCMs) associated with the forthcoming IPCC Fourth Assessment Report. Comparison of the model derived density, temperature and salinity of these water masses with observations reveals sizeable errors in these quantities in some of the models. The net heat and mass fluxes by SAMW/AAIW from the Southern Ocean into the Atlantic, Pacific and Indian oceans for the climates of the 20th and 21st centuries are then diagnosed from these GCM simulations. The resulting values are compared between GCMs as well as with the estimates of these fluxes for the 20th century climate from an observational inverse model of the Southern Ocean. The analysis identifies a group of four models that exhibit the smallest errors in SAMW/AAIW properties and show the best agreement with the inverse model estimates of property fluxes.