Warm and cold water routes of an OGCM thermohaline conveyor belt

A global general circulation model analyzed with a Lagrangian methodology is used to describe and quantify the paths, transports, and characteristics of the "warm" waters forming the upper branch of the conveyor belt in the North Atlantic Ocean. The total transport for this branch turns out to be 17.8 Sv in the North Atlantic at 20 degrees N: 11.8 Sv are composed of waters coming from the two classical origins, the Drake Passage and the Indonesian Throughflow which contribute with 6.5 and 5.3 Sv respectively. The remaining 6 Sv find their origins partly in the passage between Antarctica and the Australian Continent (with 3.1 Sv) and partly in the Indo-Atlantic sector itself (i.e., with 2.9 Sv). The geographical structure of the different routes emphasizes the role of the Southern Ocean and large-scale current systems in water mass transformation and distribution.