Changes in the geometry and strength of the Atlantic meridional overturning circulation during the last glacial (20–50 ka)

Pierre Burckel, Claire Waelbroeck, Yiming Luo, Didier M. Roche, Sylvain Pichat, Samuel L. Jaccard, Jeanne Gherardi, Aline Govin, Jörg Lippold, François Thil
2016 Climate of the Past  
<p><strong>Abstract.</strong> We reconstruct the geometry and strength of the Atlantic meridional overturning circulation during the Heinrich stadial 2 and three Greenland interstadials of the 20–50<span class="thinspace"></span>ka period based on the comparison of new and published sedimentary <sup>231</sup>Pa<span class="thinspace"></span>/<span class="thinspace"></span><sup>230</sup>Th data with simulated sedimentary <sup>231</sup>Pa<span class="thinspace"></span>/<span
more » ... an><sup>230</sup>Th. We show that the deep Atlantic circulation during these interstadials was very different from that of the Holocene. Northern-sourced waters likely circulated above 2500<span class="thinspace"></span>m depth, with a flow rate lower than that of the present-day North Atlantic deep water (NADW). Southern-sourced deep waters most probably flowed northwards below 4000<span class="thinspace"></span>m depth into the North Atlantic basin and then southwards as a return flow between 2500 and 4000<span class="thinspace"></span>m depth. The flow rate of this southern-sourced deep water was likely larger than that of the modern Antarctic bottom water (AABW). Our results further show that during Heinrich stadial 2, the deep Atlantic was probably directly affected by a southern-sourced water mass below 2500<span class="thinspace"></span>m depth, while a slow, southward-flowing water mass originating from the North Atlantic likely influenced depths between 1500 and 2500<span class="thinspace"></span>m down to the equator.</p>
doi:10.5194/cp-12-2061-2016 fatcat:wsm3bp2zo5dypnad3myli46zfa