Exchanges Between Hemispheres and Gyres: A Direct Approach to the Mean Circulation of the Equatorial Pacific
Abstract
The pathways for cross-equatorial and cross-gyre exchange are studied with an extensive set of new high-quality hydrographic data. Use of repeat surveys or comparison with historical data ensured that the data reflect mean conditions. An inverse model adjusts the circulation such that volume, heat and salt are conserved in subthermocline layers. Cross-equatorial flow is achieved in the abyss in a deep western boundary current which transports 10 Sv (=1xl0(exp 6)/cu m/s) of dense Southern Ocean water into the North Pacific. This flow returns southward as warmer deep water, crossing the equator in the interior by some unknown mechanism. In the upper ocean, subtropical gyre waters flow equatorward and entrain in the eastward equatorial currents which in turn feed the eastern Pacific upwelling system. The upwelled waters supply the South Equatorial Current, accounting for a larger transport than predicted by Sverdrup theory. Surface northward flow across the equator in the western Pacific supplies the North Pacific Ekman flux. The Pacific Ocean does not convert large mounts of abyssal to thermocline water, as required by several theories of the global thermohaline circulation. The Pacific-Indian throughflow is essentially zero, though an error analysis allows a range of 0-8 Sv. Pacific, Equatorial, Circulation.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1993
- Accession Number
- ADA279437
Entities
People
- Susan E. Wijffels
Organizations
- Woods Hole Oceanographic Institution