Modelling the relationship between 231 Pa / 230 Th distribution in North Atlantic sediment and Atlantic Meridional Overturning Circulation
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چکیده
Down-core variations in North Atlantic Paxs / Thxs have been interpreted as changes in the strength of the Atlantic Meridional Overturning Circulation (AMOC). This modelling study confirms that hypothetical changes in the AMOC would indeed be recorded as changes in the distribution of sedimentary Paxs / Thxs. At different sites in the North Atlantic the changes in sedimentary Pa / Th that we simulate are diverse and do not reflect a simple tendency for Paxs / Thxs to increase towards the production ratio (0.093) when the AMOC strength reduces but instead are moderated by the particle flux. In its collapsed or reduced state the AMOC does not remove Pa from the North Atlantic – instead Pa is scavenged to the North Atlantic sediment in areas of high particle flux. In this way the North Atlantic Paxs / Thxs during AMOC shut-down follows the same pattern as Paxs / Thxs in modern ocean basins with reduced rates of meridional overturning (i.e. Pacific or Indian Oceans). We suggest that
منابع مشابه
231Pa/230Th evidence for a weakened but persistent Atlantic meridional overturning circulation during Heinrich Stadial 1.
The strength of Atlantic meridional overturning circulation is believed to affect the climate over glacial-interglacial and millennial timescales. The marine sedimentary (231)Pa/(230)Th ratio is a promising paleocirculation proxy, but local particle effects may bias individual reconstructions. Here we present new Atlantic sedimentary (231)Pa/(230)Th data from the Holocene, the last glacial maxi...
متن کاملReply to comment by S . Peacock on “ Glacial ‐ interglacial circulation changes inferred from 231 Pa / 230 Th sedimentary record in the North Atlantic region ”
[1] Peacock [2010, P10 hereafter] takes issue with several aspects of our recent article [Gherardi et al., 2009, G09 hereafter]: (1) our description of the modern Atlantic meridional overturning circulation (AMOC), (2) apparent inconsistencies between modern circulation and our Holocene sedimentary Pa/Th bathymetric profile, and (3) our use of cores for reconstructing AMOC from locations that d...
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