HR: 16:20h
AN: OS24A-01    [Abstracts]
TI: Western PIRATA upper ocean circulation and water masses
AU: * Urbano, D F
EM: dfurbano@cptec.inpe.br
AU: Nobre, P
EM: pnobre@cptec.inpe.br
AB: Shipboard PIRATA ADCP and CTD data collected along 38°W from 1999 to 2005 provide seven meridional sections of simultaneous mass and direct velocity fields from the South American coast to 15°N. The Equatorial Undercurrent (EUC) depicts a multiple-core structure in all cruises with two main cores above and below the the 20°C, respectively. High salinity and high dissolved oxygen associated with one of the EUC cores strongly suggest that the thermocline is ventilated by both South and North Atlantic subtropical waters, the Subtropical-Tropical Cells (STC). Therefore, the EUC structure at 38°W shows to be much more complex then thought, consequently it is a key-region on subtropical-tropical exchange, and therefore on climate issues. Thermocline ventilation also occurs in the North Equatorial Undercurrent (NEUC). However, whether this subtropical water is from South or North Hemisphere is still inconclusive. The PIRATA data also provide direct measurements of the northern branch of the wind driven North Equatorial Coutercurrent (nNECC), which lies between 8°N and 14°N, and carries both North and South Atlantic waters. The two NECC cores are 4° apart from each other during boreal winter-spring (FEB1999, MAR2000, APR2002) but connected during summer cruises (JUL2003, JUL2004, and JUL2005). Inter-annual to decadal variability in the Subtropical South and North Atlantic subduction regions affect the circulation in the tropical region through the STCs. Ocean circulation is one of the dynamical mechanisms determining the patterns of the tropical Sea Surface Temperature (SST). Small changes in the SST field is able to trigger atmospheric convective process, which is closely connected with the climate over South America and Africa continents.
DE: 4231 Equatorial oceanography
DE: 4262 Ocean observing systems
DE: 4283 Water masses
DE: 4512 Currents
DE: 4532 General circulation (1218, 1222)
SC: Ocean Sciences [OS]
MN: 2007 Joint Assembly