Persistent monsoonal forcing of mediterranean outflow water dynamics during the late Pleistocene

A. Bahr*, S. Kaboth, F. J. Jiménez-Espejo, F. J. Sierro, A. H L Voelker, L. Lourens, U. Röhl, G. J. Reichart, C. Escutia, F. J. Hernández-Molina, J. Pross, O. Friedrich

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

The mode and vigor of the global oceanic circulation critically depend on the salinity of (sub)surface water masses advected to the loci of deep-water formation. Within the Atlantic meridional overturning circulation (AMOC), an important supplier of high-salinity waters is the Mediterranean Outflow Water (MOW), discharging into the North Atlantic via the Strait of Gibraltar. Despite its importance for the North Atlantic salinity budget, the long-term dynamics of MOW production have remained poorly understood. Here we present high-resolution records of bottom-current velocity from three drill sites within the Gulf of Cádiz that document a persistent low-latitude forcing of MOW flow speed over the past ~150 k.y. We demonstrate that the African monsoon is the predominant driver of orbital-scale MOW variability via its influence on the freshwater budget of the eastern Mediterranean Sea. Consequently, MOW formation fluctuates in concert with orbital precession overprinted by centennial-scale oscillations of high-latitude origin. We further document that Northern Hemisphere summer insolation minima stimulate maximal injection of MOW-derived salt into the North Atlantic, likely strengthening the intermediate AMOC branch. The direct coupling of MOW dynamics to low-latitude climate forcing represents a hitherto neglected process for propagating (sub)tropical climate signals into the high northern latitudes.

Original languageEnglish
Pages (from-to)951-954
Number of pages4
JournalGeology
Volume43
Issue number11
Early online date24 Sept 2015
DOIs
Publication statusPublished - Nov 2015

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