[Location: Location_Category='OCEAN', Location_Type='INDIAN OCEAN', Location_Subregion1='ARABIAN SEA']
Arabian Sea Surface Temperature Pattern ReconstructionsEntry ID: NOAA_NCDC_PALEO_2006-049
Abstract: These data come from cores throughout the Arabian Sea. We measured d18O, shell
weight, and Mg/Ca of G. ruber for four distinct time horizons within the core.
Forams were subjected to a full oxidative and reductive cleaning prior to
Mg/Ca analysis, as per Boyle and Keigwin (1985) and subsequent revisions.
Mg/Ca was converted to SST using the shell weight-dependent calibration of
Rosenthal and ... Lohmann (2002). SST and d18O were used to calculate the d18O of
seawater using Mulitza et al. (2003) calibration for G. ruber.
Sea surface temperature (SST) and seawater d18O (d18Ow) were reconstructed in
a suite of sediment cores from throughout the Arabian Sea for four distinct
time intervals (0 ka, 8 ka, 15 ka, and 20 ka) with the aim of understanding
the history of the Indian Monsoon and the climate of the Arabian Sea region.
This was accomplished through the use of paired Mg/Ca and d18O measurements of
the planktonic foraminifer Globigerinoides ruber. By analyzing basin-wide
changes and changes in cross-basinal gradients, we assess both monsoonal and
regional-scale climate changes. SST was colder than present for the majority
of sites within all three paleotime slices. Furthermore, both the Indian
Monsoon and the regional Arabian Sea mean climate have varied substantially
over the past 20 kyr. The 20 ka and 15 ka time slices exhibit average negative
temperature anomalies of 2.5-3.5C attributable, in part, to the influences of
glacial atmospheric CO2 concentrations and large continental ice sheets. The
elimination of the cross-basinal SST gradient during these two time slices
likely reflects a decrease in summer monsoon and an increase in winter monsoon
strength. Changes in d18Ow that are smaller than the d18O signal due to global
ice volume reflect decreased evaporation and increased winter monsoon mixing.
SSTs throughout the Arabian Sea were still cooler than present by an average
of 1.4C in the 8 ka time slice. These cool SSTs, along with lower d18Ow
throughout the basin, are attributed to stronger than modern summer and winter
monsoons and increased runoff and precipitation. The results of this study
underscore the importance of taking a spatial approach to the reconstruction
of processes such as monsoon upwelling.
Data Set Citation
Dataset Originator/Creator: Dahl, K.A. and D.W. Oppo
Dataset Title: Arabian Sea Surface Temperature Pattern Reconstructions
Dataset Series Name: IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2006-049
Dataset Release Date: 5/2006
Dataset Release Place: Boulder,CO
Dataset Publisher: IGBP PAGES/World Data Center for Paleoclimatology
Issue Identification: 2006-049
Other Citation Details: NOAA/NCDC Paleoclimatology ProgramOnline Resource: ftp://ftp.ncdc.noaa.gov/pub/data/paleo/paleocean/by_contributor/dah...
Paleo Temporal Coverage
ISO Topic Category
Use Constraints FUNDING SOURCES: Analyses were funded by National Science Foundation (USA)
SGER grant OCE03-34598. Funding was also provided by a Schlanger Ocean
Drilling Program Fellowship (to K.A.D.) and NSF grant OCE02-20776 (to D.W.O.).
Data Set Progress
Distribution Media: ftp
Distribution Format: text, excel
University of California
City: San Diego
Province or State: CA
Phone: (508) 289-2861
Email: doppo at whoi.edu
Woods Hole Oceanographic Institution MS 23, 117A Clark
City: Woods Hole
Province or State: MA
Postal Code: 02543
Dahl, K.A. and D.W. Oppo. 2006. Sea surface temperature pattern
reconstructions in the Arabian Sea. Paleoceanography, v. 21, PA1014,
Creation and Review Dates
DIF Creation Date: 2006-11-13
Last DIF Revision Date: 2006-11-20