Effect of the Missing Indonesian Throughflow in the Fine Resolution Antarctic Model

Abstract

Abstract South of Tasmania, the Fine Resolution Antarctic Model (FRAM) shows a narrow band of westward flow in the surface layer. The authors argue that this is caused by the closure of the Indonesian passage in FRAM. This is supported by numerical experiments carried out by Hirst and Godfrey and by recent radiocarbon observations in the Great Australian Bight (Ribbe et al.). The FRAM surface temperature and salinity distribution exhibits distinct anomalies in the southeast Indian Ocean, in good agreement with anomalies observed in the Hirst and Godfrey model. Indonesian Throughflow water advects heat into the Indian Ocean; its absence in FRAM results in a lack of thermal energy to warm the Indian Ocean in the model. The surface salinity anomaly is most likely caused by an overestimated Ekman transport. The weakened heat and salinity transport in FRAM restricts surface convection in the midlatitude region to approximately 350 m. The effect of the Indonesian Throughflow closure in FRAM is even more dramati...