Rbiative timing of precipitation and ocean circui In changes in the western equatorial Atlantic over the last 45 kyr
|Author(s)||Waelbroeck Claire1, Pichat Sylvain2, 3, Bohm Evelyn1, Lougheed Bryan C.1, Faranda Davide1, Vrac Mathieu1, Missiaen Lise1, Vazquez Riveiros Natalia1, 4, Burckel Pierre5, Lippold Joerg6, Arz Helge W.7, Dokken Trond8, Thil Francois1, Dapoigny Arnaud1|
|Affiliation(s)||1 : UVSQ, CEA, Lab CNRS, LSCE,IPSL, F-91198 Gif Sur Yvette, France.
2 : Univ Lyon, CNRS,UMR5276, Ecole Normale Super Lyon, Lab Geol Lyon LGL TPE, F-69007 Lyon, France.
3 : Max Planck Inst Chem, Climate Geochem Dept, Mainz, Germany.
4 : Ifremer, Unite Geosci Marines, F-29280 Plouzane, France.
5 : Univ Sorbonne, IPGP, F-75238 Paris, France.
6 : Heidelberg Univ, Inst Earth Sci, Neuenheimer Feld 234, D-69120 Heidelberg, Germany.
7 : Leibniz Inst Balt Sea Res Warnemunde, Seestr 15, D-18119 Rostock, Germany.
8 : Uni Res & Bjreknes Ctr Climate Res, Nygardsgaten 112, N-5008 Bergen, Norway.
|Source||Climate Of The Past (1814-9324) (Copernicus Gesellschaft Mbh), 2018-09 , Vol. 14 , N. 9 , P. 1315-1330|
|WOS© Times Cited||5|
Thanks to its optimal location on the northern Brazilian margin, core MD09-3257 records both ocean circulation and atmospheric changes. The latter occur locally in the form of increased rainfall on the adjacent continent during the cold intervals recorded in Greenland ice and northern North Atlantic sediment cores (i.e., Greenland stadials). These rainfall events are recorded in MD09-3257 as peaks in ln(Ti / Ca). New sedimentary Pa / Th data indicate that mid-depth western equatorial water mass transport decreased during all of the Greenland stadials of the last 40 kyr. Using cross-wavelet transforms and spectrogram analysis, we assess the relative phase between the MD09-3257 sedimentary Pa / Th and ln(Ti/Ca) signals. We show that decreased water mass transport between a depth of similar to 1300 and 2300 m in the western equatorial Atlantic preceded increased rainfall over the adjacent continent by 120 to 400 yr at Dansgaard-Oeschger (D-O) frequencies, and by 280 to 980 yr at Heinrich-like frequencies. We suggest that the large lead of ocean circulation changes with respect to changes in tropical South American precipitation at Heinrich-like frequencies is related to the effect of a positive feedback involving iceberg discharges in the North Atlantic. In contrast, the absence of widespread ice rafted detrital layers in North Atlantic cores during D-O stadials supports the hypothesis that a feedback such as this was not triggered in the case of D-O stadials, with circulation slowdowns and subsequent changes remaining more limited during D-O stadials than Heinrich stadials.