The role of North Atlantic Deep Water formation in the thermohaline circulation
An ocean general circulation model is used to explore the global ocean thermohaline circulation. North Atlantic Deep Water formation is an important component of this system and the role of this process in the ventilation, structure and variability of all the world ocean basins is studied. The production of deep water in the north Atlantic Ocean has profound effects on and around the Atlantic basin, and limited effects at certain locations downstream. A distinction is drawn between upwelling (the vertical motion of water parcels) and de-densification (the addition of buoyancy): upwelling in the model occurs primarily in the Southern Ocean and de-densification occurs mainly in the tropics between 30°S and 30°N.There are two different time-scales associated with changes in the rate of NADW formation. The adjustment time scale is quite fast, on the order of 25 years, and this is the time scale on which the overturning and heat transport in the Atlantic respond to changes in the high-latitude surface forcing. Boundary layer waves connect all three northern ocean basins and all location begin to feel a change in the rate of NADW production within 25 years. The advective time scale is much slower, on the order of 300--1000 years. The Indian and Pacific Ocean are only slightly changed by the presence or absence of NADW production in the model.
- Atmospheric sciences