HR: 0800h
AN: PP51C-1347    [Abstracts]
TI: Centennial-Scale Changes in Tropical North Atlantic Salinity Inferred from Scleractinian Corals
AU: * Moses, C S
EM: cmoses@rsmas.miami.edu
AF: University of Miami, RSMAS/MGG, 4600 Rickenbacker Cswy., Miami, FL 33149 United States
AU: Swart, P K
EM: pswart@rsmas.miami.edu
AF: University of Miami, RSMAS/MGG, 4600 Rickenbacker Cswy., Miami, FL 33149 United States
AU: Rosenheim, B E
EM: brosenheim@rsmas.miami.edu
AF: University of Miami, RSMAS/MGG, 4600 Rickenbacker Cswy., Miami, FL 33149 United States
AU: Thorrold, S
EM: sthorrold@whoi.edu
AF: Woods Hole Oceanographic Institution Biology Department, MS #35, Woods Hole, MA 02543 United States
AU: Zhang, D
EM: dongxiao.zhang@noaa.gov
AF: NOAA/PMEL, 7600 Sand Point Way NE, Seattle, WA 98115 United States
AB: Although there exist reasonably good sea-surface temperature records for most portions of the surface oceans over the past 100 years, there are poor records of salinity variations over the same time period. Salinity variations are important because when combined with temperature they govern the density of ocean water and hence oceanic circulation. Using the well established relationships between the oxygen isotopic composition of coral skeletons and temperature, it is possible to utilize the temperature records to remove this influence from the oxygen isotopic composition and thereby extract salinity records. We have applied this method to corals collected from the Cape Verde Islands in the eastern tropical Atlantic Ocean and from the Lesser Antilles in the western tropical Atlantic and compared the results to sclerosponges from the sub-tropical North Atlantic. The Cape Verde Islands are positioned at a critical juncture in the tropical Atlantic. They are located in an area which shows the highest correlation with the temperature of the north tropical Atlantic Ocean (TNA) and one where there is a steep salinity gradient associated with the presence of the sub-tropical Atlantic gyre. Salinity changes in this area are not associated with input of freshwater from either precipitation or runoff, but rather from changes in evaporation and migration of the sub-tropical Atlantic gyre. Recent work by others has suggested the presence of secular changes in the salinity of surface waters in the tropical and subtropical North Atlantic. In particular, the Salinity Maximum Waters (SMW) of the North Atlantic, generally located between 15ø-30ø N and 20ø-50ø W, have reportedly increased in salinity over the last 50-100 years. The reported increase is slight, and does not apply to the entire Atlantic, but it represents a significant change in the freshwater input, or evaporation-precipitation (E-P) balance over large sections of the Atlantic. Our data for the eastern tropical North Atlantic is based on oxygen isotopic records from three specimens of the species Siderastrea sp. from the island of Sal in the Cape Verde Islands collected in 2002. All records show poor correlation to the intra-annual temperature changes, but show similar decadal variations which between 1940 and 2000 show significant correlation to the North Atlantic Oscillation (NAO). Such correlations are similar to relationships between calculated salinity and the NAO observed in the skeletons of sclerosponges from the sub-tropical North Atlantic.
DE: 4215 Climate and interannual variability (3309)
DE: 1040 Isotopic composition/chemistry
DE: 1065 Trace elements (3670)
DE: 1620 Climate dynamics (3309)
DE: 1635 Oceans (4203)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting