DOI: 10.1016/j.epsl.2018.01.025
Scopus记录号: 2-s2.0-85044377888
论文题名: Seasonal radiogenic isotopic variability of the African dust outflow to the tropical Atlantic Ocean and across to the Caribbean
作者: Kumar A. ; Abouchami W. ; Galer S.J.G. ; Singh S.P. ; Fomba K.W. ; Prospero J.M. ; Andreae M.O.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 487 起始页码: 94
结束页码: 105
语种: 英语
英文关键词: Bodélé Depression
; dust emission
; mineral dust
; North Africa
; radiogenic Isotopes
; trans-Atlantic dust transport
Scopus关键词: Aerosols
; Image analysis
; Isotopes
; Satellite imagery
; Storms
; Strontium
; Time series
; Tropics
; Dust emission
; Dust transport
; Mineral dust
; North Africa
; Radiogenic isotopes
; Dust
英文摘要: In order to assess the impact of mineral dust on climate and biogeochemistry, it is paramount to identify the sources of dust emission. In this regard, radiogenic isotopes have recently been used successfully for tracing North African dust provenance and its transport across the tropical Atlantic to the Caribbean. Here we present two time series of radiogenic isotopes (Pb, Sr and Nd) in dusts collected at the Cape Verde Islands and Barbados in order to determine the origin of the dust and examine the seasonality of westerly dust outflow from Northern Africa. Aerosol samples were collected daily during two campaigns – February 2012 (winter) and June–July 2013 (summer) – at the Cape Verde Atmospheric Observatory (CVAO) on the island of São Vicente (16.9°N, 24.9°W). A one-year-long time series of aerosols from Barbados (13.16°N, 59.43°W) – a receptor region in the Caribbean – was sampled at a lower, monthly resolution. Our results resolve a seasonal isotopic signal at Cape Verde shown by daily variations, with a larger radiogenic isotope variability in winter compared to that in summer. This summer signature is also observed over Barbados, indicating similar dust provenance at both locations, despite different sampling years. This constrains the isotope fingerprint of Saharan Air Layer (SAL) dust that is well-mixed during its transport. This result provides unequivocal evidence for a permanent, albeit of variable strength, long-range transport of African dust to the Caribbean and is in full agreement with atmospheric models of North African dust emission and transport across the tropical Atlantic in the SAL. The seasonal isotopic variability is related to changes in the dust source areas – mainly the Sahara and Sahel regions – that are active all-year-round, albeit with variable contributions in summer versus the winter months. Our results provide little support for much dust contributed from the Bodélé Depression in Chad – the “dustiest” place on Earth – reaching Cape Verde and Barbados during the summer, while contributions during the winter months are likely patchy and minor at most. Importantly, a short-term isotopic excursion is resolved in the Cape Verde winter record during a dust outbreak on 06–08 February 2012. This features a highly radiogenic Pb and Sr and unradiogenic Nd signature, marking a clear shift in dust provenance relative to that of normal days. As the dust storm waned, continuous gradual changes are observed, reflecting mixing and progressive dilution with dust typical of normal days. These inferences from radiogenic isotope tracers are corroborated by both satellite images (CALIPSO and MODIS) and back-trajectory analyses. The radiogenic isotope fingerprinting of these presently-active North African dust sources, and especially the Saharan Air Layer, will prove invaluable in studies of past dust emission from Northern Africa, where imagery and back trajectory analysis are unavailable. © 2018 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/110006
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: Biogeochemistry and Climate Geochemistry Departments, Max Planck Institute for Chemistry, P.O. Box 3060, Mainz, 55020, Germany; CSIR-National Institute of Oceanography, Dona Paula, Goa, 403 004, India; Institut für Mineralogie, WWU Münster, Corrensstraße 24, Münster, 48149, Germany; Institut de Physique du Globe de Paris, 1 Rue Jussieu, Paris, 75005, France; Indian Institute of Science Education and Research Bhopal, Department of Earth and Environmental Sciences, Bhopal, Madhya Pradesh 462 066, India; Department of Chemistry, Leibniz Institute for Tropospheric Research, Leipzig, Germany; The Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL 33149-1098, United States; Geology and Geophysics Department, King Saud University, Riyadh, Saudi Arabia
Recommended Citation:
Kumar A.,Abouchami W.,Galer S.J.G.,et al. Seasonal radiogenic isotopic variability of the African dust outflow to the tropical Atlantic Ocean and across to the Caribbean[J]. Earth and Planetary Science Letters,2018-01-01,487