Past African dust inputs in the western Mediterranean area controlled by the complex interaction between the Intertropical Convergence Zone, the North Atlantic Oscillation, and total solar irradiance

North Africa is the largest source of mineral dust on Earth, which has multiple impacts on the climate system; however, our understanding of decadal to centennial changes in African dust emissions over the last few millenniums is limited. Here, we present a high-resolution multiproxy analysis of sed...

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Published in:	Climate of the past Vol. 16; no. 1; pp. 283 - 298
Main Authors:	Sabatier, Pierre, Nicolle, Marie, Piot, Christine, Colin, Christophe, Debret, Maxime, Swingedouw, Didier, Perrette, Yves, Bellingery, Marie-Charlotte, Chazeau, Benjamin, Develle, Anne-Lise, Leblanc, Maxime, Skonieczny, Charlotte, Copard, Yoann, Reyss, Jean-Louis, Malet, Emmanuel, Jouffroy-Bapicot, Isabelle, Kelner, MaÃ«lle, Poulenard, Jérôme, Didier, Julien, Arnaud, Fabien, Vannière, Boris
Format:	Journal Article
Language:	English
Published:	Katlenburg-Lindau Copernicus GmbH 07-02-2020 European Geosciences Union (EGU) [2005-....] Copernicus Publications
Subjects:	Analysis Atmospheric and Oceanic Physics Atmospheric forcing Atmospheric particulates Clay Clay minerals Climate Climate cycles Climate system Climatology Convergence Convergence zones Decadal variations Dust Dust control Dust deposition Dust storms Dust transport Earth Earth Sciences Fluxes Geochemistry High resolution Intertropical convergence zone Irradiance Lake sediments Lakes Long-term changes Mineralogy North Atlantic Oscillation Ocean-atmosphere system Palygorskite Physics Proxy Resolution Saharan dust Sciences of the Universe Solar irradiance Solar oscillations Terrigenous sediments Transport Variation Wavelet analysis Wind Northern Africa North Africa
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Summary:	North Africa is the largest source of mineral dust on Earth, which has multiple impacts on the climate system; however, our understanding of decadal to centennial changes in African dust emissions over the last few millenniums is limited. Here, we present a high-resolution multiproxy analysis of sediment core from high-elevation Lake Bastani, on the island of Corsica, to reconstruct past African dust inputs to the western Mediterranean area over the last 3150 cal BP. Clay mineralogy with palygorskite and a clay ratio associated with geochemical data allow us to determine that terrigenous fluxes are almost exclusively related to atmospheric dust deposition from the western Sahara and Sahel areas over this period. High-resolution geochemical contents provide a reliable proxy for Saharan dust inputs with long-term (millennial) to short-term (centennial) variations. Millennial variations have been correlated with the long-term southward migration of the Intertropical Convergence Zone (ITCZ), with an increase in dust input since 1070 cal BP. This correlation suggests a strong link with the ITCZ and could reflect the increased availability of dust sources to be mobilized with an increase in wind and a decrease in precipitation over western and North Africa. For centennial to decadal variations, wavelet analyses show that since 1070 cal BP, the North Atlantic Oscillation (NAO) has been the main climatic forcing, with an increase in Saharan dust input during the positive phase, as suggested by previous studies over the last decades. However, when the ITCZ is in a northern position, before 1070 cal BP, wavelet analyses indicate that total solar irradiance (TSI) is the main forcing factor, with an increase in African dust input during low TSI. With climate reanalysis over the instrumental era, during low TSI we observe a significant negative anomaly in pressure over Africa, which is known to increase the dust transport. These two climatic forcing factors (NAO, TSI) modulate Saharan dust inputs to the Mediterranean area at a centennial timescale through changes in wind and transport pathways.
ISSN:	1814-9332 1814-9324 1814-9332
DOI:	10.5194/cp-16-283-2020