IUGG 2003 Abstract

P01 Western Boundary Currents Wednesday, July 2 AM Location: Site B, Room 18 Presiding Chairs:D.K. Olson, S. Imawaki

TIME [ 1010 ] [ P01/02A/B18-005 ]

SOURCES AND FATE OF EQUATORIAL UNDERCURRENTS

Wilco HAZELEGER(Oceanogr. Res., Royal Netherlands Meteorological Institute (KNMI))

Pedro DE VRIES(Oceanogr. Res., Royal Netherlands Meteorological Institute (KNMI)) Paul GOODMAN ( Lamont-Doherty Earth Observatory of Columbia Univ, Palisades, NY, USA ) Mark CANE ( Lamont-Doherty Earth Observatory of Columbia Univ, Palisades, NY, USA )

The sources and fate of the EUC in the Atlantic and Pacific are studiedusing a high-resolution ocean model (OCCAM, dx=0.25 degree).Water masses are traced backwardand forward in time from the core of the EUC with a Lagrangianmethod taking high-frequency variability into account.In the Atlantic, most of the ventilated water in the EUCoriginates from the South Atlantic. The ventilated water follows the SouthEquatorial Currentto the western boundary. Only 1/10th of the transport reaching the EUCtakes an interior pathway.EUC water upwells mostly at the equator. 1/3rd of EUC transportat 20W takes part in the STCand 2/3rds leave the Atlantic basin to take part in the MOC. These parcelsare subject to multiple up- and downwellings.In the Pacific, 2/3rds of the water masses in the EUCoriginates from the Southern Hemisphere, 1/3rd from the Northern Hemisphere.Water masses take a circuitous route along the subtropical gyres to thewestern boundary currents. Most transformation of water masses takes placebefore entering the western boundary currents.In the Atlantic and Pacific, the western boundary currents are the mainagents for transporting water masses from the extratropics to the tropics.