HR: 10:35h
AN: PP12A-02    [Abstracts]
TI: Reconstructing Arabian Sea Sea Surface Temperatures from the Last Glacial Maximum to the Present using foraminiferal Mg/Ca
AU: * Dahl, K A
EM: kdahl@whoi.edu
AF: MIT/WHOI Joint Program Department of Marine Geology and Geophysics, WHOI MS #22, Woods Hole, MA 02543 United States
AU: Oppo, D W
EM: doppo@whoi.edu
AF: Woods Hole Oceanographic Institution Department of Marine Geology and Geophysics, WHOI MS #23, Woods Hole, MA 02543 United States
AB: The strong southwestly winds of the summer Indian Monsoon induce intense upwelling along the margin of the Arabian Peninsula. Paleoclimatological reconstructions of the Indian Monsoon have historically relied heavily on the assumption that sea surface temperature (SST) in the western Arabian Sea is dominantly controlled by summer monsoon strength. While this assumption does appear to hold true for today's climate, preliminary data, obtained by spatially mapping SST patterns across the Arabian Sea for three time horizons (8~kyr, 15~kyr, and 20~kyr B.P.) using a suite of sediment cores from throughout the basin, suggest that upwelling strength is only one of several factors controlling SST along the Arabian Peninsula on longer time scales. The 20~kyr time slice, for example, demonstrates that SSTs from both upwelling and non--upwelling regions of the Arabian Sea were significantly cooler ($\sim$3$^{\circ}$C) than today. Changes in SST as a result of changes in upwelling in the western Arabian Sea are therefore superimposed on a larger--scale, basin--wide cooling. Given this knowledge, we have produced a record of SST and salinity along the Oman Margin using paired Mg/Ca and $\delta^{18}$O analyses on two species of planktonic foraminifera, \emph{Globigerina bulloides} and \emph{Globigernoides ruber}. The record spans the time period from the Last Glacial Maximum to the present, during which large changes in the Indian Monsoon have been implied from other paleoclimatological reconstructions. We use the time--slice maps that we have produced to provide a broader context, albeit limited in the time domain, for the changes in SST we observe along the Oman Margin. Our record serves as a compliment to records from nearby cores of \emph{G. bulloides} abundance, assumed to reflect upwelling intensity, while providing a more quantitative view of SST changes over the past 20~kyr.
DE: 3344 Paleoclimatology
DE: 4267 Paleoceanography
DE: 1854 Precipitation (3354)
DE: 1620 Climate dynamics (3309)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting