Fig. 1b. Sea surface salinity during the boreal winter (northwest monsoon) (January-March)
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Holocene evolution of the Indonesian throughflow and the western Pacific warm pool
Nature Geoscience
Vol. 3, pp. 578-583, August 2010.
DOI: 10.1038/NGEO920
Braddock K. Linsley1, Yair Rosenthal2, and Delia W. Oppo3
1 Department of Atmospheric and Environmental Sciences, University at Albany-State University of New York, Albany, New York 12222, USA
2 Institute of Marine and Coastal Sciences, and Department of Earth and Planetary Sciences, Rutgers, The State University, New Brunswick, New Jersey 08901, USA
3 Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA
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ABSTRACT:
High sea surface temperatures in the western Pacific warm pool
fuel atmospheric convection and influence tropical climate.
This region also hosts the Indonesian throughflow, the network
of currents through which surface and thermocline waters are
transported from the western equatorial Pacific Ocean into the
Indian Ocean. Here we show, using records of the d18O and Mg/Ca
of planktonic foraminifera from eight sediment cores, that from
about 10,000 to 7,000 years ago, sea surface temperatures in the
western sector of the western Pacific warm pool were about 0.5°C
higher than during pre-industrial times. We also find that
about 9,500 years ago, when the South China and Indonesian
seas were connected by rising sea level, surface waters in the
Makassar Strait became relatively fresher. We suggest that the
permanent reduction of surface salinity initiated the enhanced
flow at lower, thermocline depths seen in the modern Indonesian
throughflow. However, the uniformly warm sea surface temperatures
found upstream and downstream of the Indonesian throughflow
indicate that the early Holocene warmth in this region was not
directly related to reduced heat transport by the throughflow
that may have resulted from surface freshening of the Makassar
Strait. Instead, we propose that the elevated temperatures were
the result of a westward shift or expansion of the boundaries
of the western Pacific warm pool.
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