In:
Climate of the Past, Copernicus GmbH, Vol. 16, No. 1 ( 2020-02-07), p. 283-298
Abstract:
Abstract. 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.
Type of Medium:
Online Resource
ISSN:
1814-9332
DOI:
10.5194/cp-16-283-2020
DOI:
10.5194/cp-16-283-2020-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2020
detail.hit.zdb_id:
2217985-9
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