HR: 16:15h
AN: PP54A-02 INVITED     [Abstracts]
TI: Decadal Scale Variability in the Subtropical North Atlantic Shallow Thermohaline Circulation
AU: * Rosenheim, B E
EM: brosenheim@whoi.edu
AF: Woods Hole Oceanographic Institution, MS #8, Woods Hole, MA 02543 United States
AU: Moses, C S
EM: cmoses@marine.usf.edu
AF: University of South Florida, Institute for Marine Remote Sensing College of Marine Sciences 140 7th Avenue South, St. Petersburg, FL 33701 United States
AU: Swart, P K
EM: pswart@rsmas.miami.edu
AF: University of Miami Rosenstiel School for Marine and Atmospheric Science, 4600 Rickenbacker Causeway, Miami, FL 33149 United States
AB: Recently published salinity records from subsurface proxies archived in sclerosponge skeletons show links between the subtropical convection cell (STC) of the N. Atlantic Ocean and the North Atlantic Oscillation (NAO) by virtue of changes in the Azores high pressure. This convection cell outcrops to the surface ocean in two regions - the salinity maximum waters (SMW) of the N. Atlantic Subtropical Gyre return flow and at the equator and northeastern coast of South America. The STC receives surplus atmospheric heat in the equatorial upwelling region and returns this heat latently at higher latitudes where it forms the SMW and subducts along isopycnal surfaces. The surface flow path of this cell is not as well constrained as the subsurface flow path, however strong communication with the N. Atlantic gyre and the formation of deep water is likely. Thus, investigation of the nature and possible causes of decadal STC variability, as well as long term changes, may enhance our understanding of similar magnitude changes in the deep water formation and the Gulf Stream transport. Soon to be published coral proxy records from the eastern tropical Atlantic lend corroboration to the story contained in sclerosponge temperature and salinity proxies. The coral stable isotope records seem to be dominated by the water signal rather than the temperature signal, which, in turn, shows a significant relationship with the NAO. The fortuitous location of these corals along with a decoupling from coherent variation with the NAO in the early 1900's suggest that the SMW is not always located in the same distinct geographic region despite continuously ventilating the subsurface Caribbean with subtropical underwater. Subsurface sclerosponge records show a possible increase in the proportion of N. Atlantic water contributed to the subtropical underwater, but without the help of the surface records from corals, they cannot begin to discern from where the water mass originates. Both the variability in amount of and subduction location of the subsurface ventilating SMW may contribute to variability of the N. Atlantic deep water ventilation.
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1635 Oceans (1616, 3305, 4215, 4513)
DE: 4512 Currents
DE: 4962 Thermohaline
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005