Mass, heat and nutrient fluxes in the Atlantic Ocean determined by inverse methods

• Main Author: Rintoul, Stephen R.
• Format: Thesis
• Language: English
• Published: Massachusetts Institute of Technology and Woods Hole Oceanographic Institution 1988
• Subjects: Ocean circulation; Ocean temperature; Conrad (Ship) Cruise; Atlantis II (Ship : 1963-) Cruise AII109; Antarctic; Drake Passage; Indian; The Antarctic; Antarc*; NADW; North Atlantic Deep Water; North Atlantic
• Online Access: https://hdl.handle.net/1912/4759

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution March 1988 Inverse methods are applied to historical hydrographic data to address two aspects of the general circulation of the Atlantic Ocean. The method allows conservation statements for mass and other properties, along with a variety of other constraints, to be combined in a dynamically consistent way to estimate the absolute velocity field and associated property transports. The method is first used to examine the exchange of mass and heat between the South Atlantic and the neighboring ocean basins. The Antarctic Circumpolar Current (ACC) carries a surplus of intermediate water into the South Atlantic through Drake Passage which is compensated by a surplus of deep and bottom water leaving the basin south of Africa. As a result, the ACC loses .25±.18x1015 W of heat in crossing the Atlantic. At 32°S the meridional flux of heat is .25±.19x1015 W equatorward, consistent in sign but smaller in magnitude than other recent estimates. This heat flux is carried primarily by a meridional overturning cell in which the export of 17 Sv of North Atlantic Deep Water (NADW) is balanced by an equatorward return flow equally split between the surface layers, and the intermediate and bottom water. No "leak" of warm Indian Ocean thermocline water is necessary to account for the equatorward heat flux across 32°S; in fact, a large transfer of warm water from the Indian Ocean to the Atlantic is found to be inconsistent with the present data set. Together these results demonstrate that the Atlantic as a whole acts to convert intermediate water to deep and bottom water, and thus that the global thermohaline cell associated with the formation and export of NADW is closed primarily by a "cold water path," in which deep water leaving the Atlantic ultimately returns as intermediate water entering the basin through Drake Passage. The second problem ...