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...
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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 |
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English |
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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 |
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Atmospheric Chemistry and Physics |
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16 |
container_issue |
21 |
container_start_page |
13697 |
op_container_end_page |
13710 |
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1766133745501339648 |