Posted by Alex Ganachaud on May 11, 2001 at 01:00:04:
This poster shows evidence, based on Levitus data and a low resolution GCM, for a third return path of upper water to the North Atlantic. The GCM ORCA is relaxed towards LEVITUS data, except near boundaries, and the monthly velocity fields are used to diagnose the lagrangian path of water particles. It is then possible to distinguish the origins of upper, northward-flowing waters of the Equatorial Atlantic.
I found the poster very attractive. Water mass analysis seem to confirm the Indian Ocean intermediate water flow suggested here (see Toole and Warren, 1993). The flow immediately south of Australia is also westward, according to observations.
My interpretation of this method is that the ORCA model provides a circulation scheme which is consistent with Levitus and ocean dynamics. As a result, the flow should be in agreement with large scale property distribution, and one has a powerful tool to quantify the water mass transports and their origins.