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On the decadal scale correlation between African dust and Sahel rainfall: The role of Saharan heat low–forced winds

A large body of work has shown that year-to-year variations in North African dust emission are inversely proportional to previous-year monsoon rainfall in the Sahel, implying that African dust emission is highly sensitive to vegetation changes in this narrow transitional zone. However, such a theory...

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Autores principales: Wang, Weijie, Evan, Amato T., Flamant, Cyrille, Lavaysse, Christophe
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Association for the Advancement of Science 2015
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4646815/
https://www.ncbi.nlm.nih.gov/pubmed/26601301
http://dx.doi.org/10.1126/sciadv.1500646
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author Wang, Weijie
Evan, Amato T.
Flamant, Cyrille
Lavaysse, Christophe
author_facet Wang, Weijie
Evan, Amato T.
Flamant, Cyrille
Lavaysse, Christophe
author_sort Wang, Weijie
collection PubMed
description A large body of work has shown that year-to-year variations in North African dust emission are inversely proportional to previous-year monsoon rainfall in the Sahel, implying that African dust emission is highly sensitive to vegetation changes in this narrow transitional zone. However, such a theory is not supported by field observations or modeling studies, as both suggest that interannual variability in dust is due to changes in wind speeds over the major emitting regions, which lie to the north of the Sahelian vegetated zone. We reconcile this contradiction showing that interannual variability in Sahelian rainfall and surface wind speeds over the Sahara are the result of changes in lower tropospheric air temperatures over the Saharan heat low (SHL). As the SHL warms, an anomalous tropospheric circulation develops that reduces wind speeds over the Sahara and displaces the monsoonal rainfall northward, thus simultaneously increasing Sahelian rainfall and reducing dust emission from the major dust “hotspots” in the Sahara. Our results shed light on why climate models are, to date, unable to reproduce observed historical variability in dust emission and transport from this region.
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spelling pubmed-46468152015-11-23 On the decadal scale correlation between African dust and Sahel rainfall: The role of Saharan heat low–forced winds Wang, Weijie Evan, Amato T. Flamant, Cyrille Lavaysse, Christophe Sci Adv Research Articles A large body of work has shown that year-to-year variations in North African dust emission are inversely proportional to previous-year monsoon rainfall in the Sahel, implying that African dust emission is highly sensitive to vegetation changes in this narrow transitional zone. However, such a theory is not supported by field observations or modeling studies, as both suggest that interannual variability in dust is due to changes in wind speeds over the major emitting regions, which lie to the north of the Sahelian vegetated zone. We reconcile this contradiction showing that interannual variability in Sahelian rainfall and surface wind speeds over the Sahara are the result of changes in lower tropospheric air temperatures over the Saharan heat low (SHL). As the SHL warms, an anomalous tropospheric circulation develops that reduces wind speeds over the Sahara and displaces the monsoonal rainfall northward, thus simultaneously increasing Sahelian rainfall and reducing dust emission from the major dust “hotspots” in the Sahara. Our results shed light on why climate models are, to date, unable to reproduce observed historical variability in dust emission and transport from this region. American Association for the Advancement of Science 2015-10-09 /pmc/articles/PMC4646815/ /pubmed/26601301 http://dx.doi.org/10.1126/sciadv.1500646 Text en Copyright © 2015, The Authors http://creativecommons.org/licenses/by-nc/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license (http://creativecommons.org/licenses/by-nc/4.0/) , which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited.
spellingShingle Research Articles
Wang, Weijie
Evan, Amato T.
Flamant, Cyrille
Lavaysse, Christophe
On the decadal scale correlation between African dust and Sahel rainfall: The role of Saharan heat low–forced winds
title On the decadal scale correlation between African dust and Sahel rainfall: The role of Saharan heat low–forced winds
title_full On the decadal scale correlation between African dust and Sahel rainfall: The role of Saharan heat low–forced winds
title_fullStr On the decadal scale correlation between African dust and Sahel rainfall: The role of Saharan heat low–forced winds
title_full_unstemmed On the decadal scale correlation between African dust and Sahel rainfall: The role of Saharan heat low–forced winds
title_short On the decadal scale correlation between African dust and Sahel rainfall: The role of Saharan heat low–forced winds
title_sort on the decadal scale correlation between african dust and sahel rainfall: the role of saharan heat low–forced winds
topic Research Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4646815/
https://www.ncbi.nlm.nih.gov/pubmed/26601301
http://dx.doi.org/10.1126/sciadv.1500646
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