The Indian Ocean as a Connector

The Indian Ocean is a conduit for the upper ocean flow of the global thermohaline circulation. It receives water from the Pacific Ocean through the Indonesian throughflow and the Tasman leakage, and exports water into the Atlantic by means of Agulhas leakage. A small contribution from the northern Indian Ocean is also detectable within Agulhas leakage. Changes on different timescales in the various components of the Pacific inflows and the Atlantic outflow have been reported. Little is known on the role of the Indian Ocean circulation in communicating changes from the Pacific into the Atlantic, let alone any eventual alterations in response to climate change. The precise routes and timescales of Indonesian throughflow, Tasman leakage, Red Sea and Persian Gulf Waters towards the Atlantic are examined in a Lagrangian framework within a high-resolution global ocean model. In this presentation, the following questions are addressed: How are Pacific waters modified in the Indian Ocean before reaching the Agulhas system? On what timescale is water that enters the Indian Ocean from the Pacific flushed out? How important are detours in the Bay of Bengal and Arabian Sea?