Warm and cold water routes of an OGCM thermohaline conveyor belt

A global general circulation model analyzed with a Lagrangian methodology i s used to describe and quantify the paths, transports, and characteristics of the "warm" waters forming the upper branch of the conveyor belt in the N orth 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 Indonesia n Throughflow which contribute with 6.5 and 5.3 Sv respectively. The remain ing 6 Sv find their origins partly in the passage between Antarctica and th e 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 ro utes emphasizes the role of the Southern Ocean and large-scale current syst ems in water mass transformation and distribution.