HR: 16:30h
AN: PP54A-03    [Abstracts]
TI: Abrupt Freshening of Subtropical North Pacific Surface Waters in the Early 20th Century?
AU: * Felis, T
EM: tfelis@uni-bremen.de
AF: DFG-Research Center for Ocean Margins, University of Bremen, Bremen, 28359 Germany
AU: Suzuki, A
PP54A-03 AF: Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 305-8567 Japan
AU: Kuhnert, H
PP54A-03 AF: DFG-Research Center for Ocean Margins, University of Bremen, Bremen, 28359 Germany
AU: Rimbu, N
PP54A-03 AF: Alfred-Wegener-Institute for Polar and Marine Research, Paleo-climate Dynamics, Bremerhaven, 27570 Germany
AU: Kawahata, H
PP54A-03 AF: Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 305-8567 Japan
AU: Kawahata, H
PP54A-03 AF: Ocean Research Institute, University of Tokyo, Tokyo, 164-8639 Japan
AB: Continuous instrumental records of sea surface salinity in the world ocean do not extend beyond the mid-1970s, and proxy-based reconstructions that resolve interannual to decadal salinity variations are virtually absent in the North Pacific Ocean. Here we present a reconstruction of sea surface conditions in the western subtropical North Pacific since the late 19th century; based on an annually-banded reef coral ( Porites) from Ogasawara Islands (Japan). The Ogasawara Islands are situated in the southwestward return flow of the Kuroshio recirculation system and represent one of the rare North Pacific sites where century-old corals are growing at such high latitudes (27 degrees North). The seasonally resolved coral record is based on oxygen isotopes, Sr/Ca and U/Ca. The isotopic and elemental tracers in the coral skeleton, supported by gridded estimates of sea surface temperature, suggest an abrupt freshening of the surface waters between 1906 and 1909 AD. If this apparent freshening reflects a real, large-scale phenomenon, it would be indicative of an abrupt decrease in sea surface salinity of the North Pacific subtropical gyre in the early 20th century. Possible reasons for such a decrease in sea surface salinity include changes in the intensity and/or location of the gyre, or changes in the regional hydrologic balance.
DE: 1620 Climate dynamics (0429, 3309)
DE: 4900 PALEOCEANOGRAPHY (0473, 3344)
DE: 4916 Corals (4220)
DE: 4924 Geochemical tracers
DE: 4954 Sea surface temperature
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005