INTEROCEAN EXCHANGE OF WATER MASSES

A new method for calculating water mass transport between different oc ean basins from the velocity fields obtained by numerical models is pr esented. The method is applied to the velocity field of the Southern O cean simulated by a primitive equation model (fine resolution Antarcti c model). With this method it is possible to judge whether a water mas s has been ventilated or not, to estimate how many times it has circle d around Antarctica, and to calculate the time it has spent in the Sou thern Ocean. Calculations have also been undertaken revealing to what extent the changes of temperature, salinity, and density have been cau sed by mixing and by ventilation. Two major ways to redistribute the w ater through the Southern Ocean are identified. The first one redistri butes 53% of the water and involves an unventilated direct exchange be tween the oceans, the second one redistributes 33% by going around Ant arctica. It is found that, on average, the water mass makes six circui ts before the water is ventilated and subsequently driven to the north by the Ekman transport. A heat transport study is carried out for the Atlantic, showing that the northward heat transport into the Atlantic comes 85% from the Indian Ocean and the rest from the Drake Passage.