Particle size traces modern Saharan dust transport and deposition across the equatorial North Atlantic

Mineral dust has a large impact on regional and global climate, depending on its particle size. Especially in the Atlantic Ocean downwind of the Sahara, the largest dust source on earth, the effects can be substantial but are poorly understood. This study focuses on seasonal and spatial variations i...

Full description

Bibliographic Details
Published in:Atmospheric Chemistry and Physics
Main Authors: Does, Michèlle, Korte, Laura F., Munday, Chris I., Brummer, Geert-Jan A., Stuut, Jan-Berend W.
Format: Text
Language:English
Published: 2018
Subjects:
Online Access:https://doi.org/10.5194/acp-16-13697-2016
https://www.atmos-chem-phys.net/16/13697/2016/
id ftcopernicus:oai:publications.copernicus.org:acp51003
record_format openpolar
spelling ftcopernicus:oai:publications.copernicus.org:acp51003 2023-05-15T17:34:48+02:00 Particle size traces modern Saharan dust transport and deposition across the equatorial North Atlantic Does, Michèlle Korte, Laura F. Munday, Chris I. Brummer, Geert-Jan A. Stuut, Jan-Berend W. 2018-09-10 application/pdf https://doi.org/10.5194/acp-16-13697-2016 https://www.atmos-chem-phys.net/16/13697/2016/ eng eng doi:10.5194/acp-16-13697-2016 https://www.atmos-chem-phys.net/16/13697/2016/ eISSN: 1680-7324 Text 2018 ftcopernicus https://doi.org/10.5194/acp-16-13697-2016 2019-12-24T09:51:51Z Mineral dust has a large impact on regional and global climate, depending on its particle size. Especially in the Atlantic Ocean downwind of the Sahara, the largest dust source on earth, the effects can be substantial but are poorly understood. This study focuses on seasonal and spatial variations in particle size of Saharan dust deposition across the Atlantic Ocean, using an array of submarine sediment traps moored along a transect at 12° N. We show that the particle size decreases downwind with increased distance from the Saharan source, due to higher gravitational settling velocities of coarse particles in the atmosphere. Modal grain sizes vary between 4 and 32 µm throughout the different seasons and at five locations along the transect. This is much coarser than previously suggested and incorporated into climate models. In addition, seasonal changes are prominent, with coarser dust in summer and finer dust in winter and spring. Such seasonal changes are caused by transport at higher altitudes and at greater wind velocities during summer than in winter. Also, the latitudinal migration of the dust cloud, associated with the Intertropical Convergence Zone, causes seasonal differences in deposition as the summer dust cloud is located more to the north and more directly above the sampled transect. Furthermore, increased precipitation and more frequent dust storms in summer coincide with coarser dust deposition. Our findings contribute to understanding Saharan dust transport and deposition relevant for the interpretation of sedimentary records for climate reconstructions, as well as for global and regional models for improved prediction of future climate. Text North Atlantic Copernicus Publications: E-Journals Atmospheric Chemistry and Physics 16 21 13697 13710
institution Open Polar
collection Copernicus Publications: E-Journals
op_collection_id ftcopernicus
language English
description Mineral dust has a large impact on regional and global climate, depending on its particle size. Especially in the Atlantic Ocean downwind of the Sahara, the largest dust source on earth, the effects can be substantial but are poorly understood. This study focuses on seasonal and spatial variations in particle size of Saharan dust deposition across the Atlantic Ocean, using an array of submarine sediment traps moored along a transect at 12° N. We show that the particle size decreases downwind with increased distance from the Saharan source, due to higher gravitational settling velocities of coarse particles in the atmosphere. Modal grain sizes vary between 4 and 32 µm throughout the different seasons and at five locations along the transect. This is much coarser than previously suggested and incorporated into climate models. In addition, seasonal changes are prominent, with coarser dust in summer and finer dust in winter and spring. Such seasonal changes are caused by transport at higher altitudes and at greater wind velocities during summer than in winter. Also, the latitudinal migration of the dust cloud, associated with the Intertropical Convergence Zone, causes seasonal differences in deposition as the summer dust cloud is located more to the north and more directly above the sampled transect. Furthermore, increased precipitation and more frequent dust storms in summer coincide with coarser dust deposition. Our findings contribute to understanding Saharan dust transport and deposition relevant for the interpretation of sedimentary records for climate reconstructions, as well as for global and regional models for improved prediction of future climate.
format Text
author Does, Michèlle
Korte, Laura F.
Munday, Chris I.
Brummer, Geert-Jan A.
Stuut, Jan-Berend W.
spellingShingle Does, Michèlle
Korte, Laura F.
Munday, Chris I.
Brummer, Geert-Jan A.
Stuut, Jan-Berend W.
Particle size traces modern Saharan dust transport and deposition across the equatorial North Atlantic
author_facet Does, Michèlle
Korte, Laura F.
Munday, Chris I.
Brummer, Geert-Jan A.
Stuut, Jan-Berend W.
author_sort Does, Michèlle
title Particle size traces modern Saharan dust transport and deposition across the equatorial North Atlantic
title_short Particle size traces modern Saharan dust transport and deposition across the equatorial North Atlantic
title_full Particle size traces modern Saharan dust transport and deposition across the equatorial North Atlantic
title_fullStr Particle size traces modern Saharan dust transport and deposition across the equatorial North Atlantic
title_full_unstemmed Particle size traces modern Saharan dust transport and deposition across the equatorial North Atlantic
title_sort particle size traces modern saharan dust transport and deposition across the equatorial north atlantic
publishDate 2018
url https://doi.org/10.5194/acp-16-13697-2016
https://www.atmos-chem-phys.net/16/13697/2016/
genre North Atlantic
genre_facet North Atlantic
op_source eISSN: 1680-7324
op_relation doi:10.5194/acp-16-13697-2016
https://www.atmos-chem-phys.net/16/13697/2016/
op_doi https://doi.org/10.5194/acp-16-13697-2016
container_title Atmospheric Chemistry and Physics
container_volume 16
container_issue 21
container_start_page 13697
op_container_end_page 13710
_version_ 1766133745501339648