Low Pacific reconstructed Ho2012

Core/Site name:

GeoB3388-1

Elevation:

-3558

Archive:

marine sediments (downcore)

Proxy measurement:

SST alkenones

Sampling resolution:

millennial

Startyear:

699.875 ka BP

Endyear:

9.706 ka BP

Description:

In spite of the important role played by the Southern Ocean in global climate, the few existing paleoceanographic records in the east Pacific sector do not extend beyond one glacial-interglacial cycle, hindering circumpolar comparison of past sea surface temperature (SST) evolution in the Southern Ocean. Here we present three alkenone-based Pleistocene SST records from the subantarctic and subtropical Pacific. We use a regional core top calibration data set to constrain the choice of calibrations for paleo SST estimation. Our core top data confirm that the alkenone-based UK37 and UK'37 values correlate linearly with the SST, in a similar fashion as the most commonly used laboratory culture-based calibrations even at low temperatures (down to ~1°C), rendering these calibrations appropriate for application in the subantarctic Pacific. However, these alkenone indices yield diverging temporal trends in the Pleistocene SST records. On the basis of the better agreement with d18O records and other SST records in the subantarctic Southern Ocean, we propose that the UK37 is a better index for SST reconstruction in this region than the more commonly used UK'37 index. The UK37-derived SST records suggest glacial cooling of ~8°C and ~4°C in the subantarctic and subtropical Pacific, respectively. Such extent of subantarctic glacial cooling is comparable to that in other sectors of the Southern Ocean, indicating a uniform circumpolar cooling during the Pleistocene. Furthermore, our SST records also imply massive equatorward migrations of the Antarctic Circumpolar Current (ACC) frontal systems and an enhanced transport of ACC water to lower latitudes during glacials by the Peru-Chile Current.

Data entered by name:

Martrat, Belen

Data entered by email:

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Main reference(s):

Ho, S. L. et al. Sea surface temperature variability in the Pacific sector of the Southern Ocean over the past 700 kyr. Paleoceanography 27, PA4202, doi:10.1029/2012pa002317 (2012).

Link to reference 1:

http://dx.doi.org/10.1029/2012PA002317

Data storage link 1:

http://doi.pangaea.de/10.1594/PANGAEA.792642

Current dating method:

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Annual snow acc rate:

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Category: PIGS