The pulsating nature of large-scale Saharan dust transport as a result of interplays between mid-latitude Rossby waves and the North African Dipole Intensity

It was previously shown that during August the export of Saharan dust to the Atlantic was strongly affected by the difference of the 700-hPa geopotential height anomaly between the subtropics and the tropics over North Africa, which was termed the North African Dipole Intensity (NAFDI). In this work...

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Autores: Cuevas, E., Gómez-Peláez, A.J., Rodríguez, S., Terradellas, E., Basart, S., García, R.D., García, O.E., Alonso-Pérez, S.
Formato: artículo
Fecha de publicación:2017
País:España
Recursos:Universitat Politècnica de Catalunya (UPC)
Repositorio:UPCommons. Portal del coneixement obert de la UPC
Idioma:inglés
OAI Identifier:oai:upcommons.upc.edu:2117/108640
Acesso em linha:https://hdl.handle.net/2117/108640
https://dx.doi.org/10.1016/j.atmosenv.2017.08.059
Access Level:acceso abierto
Palavra-chave:Dust--adverse effects
Sahara--Climate
Saharan dust
North African Dipole Intensity (NAFDI)
Saharan Heat Low (SHL)
Deserts--Àfrica del Nord
Sàhara
Àrees temàtiques de la UPC::Energies
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spelling The pulsating nature of large-scale Saharan dust transport as a result of interplays between mid-latitude Rossby waves and the North African Dipole IntensityCuevas, E.Gómez-Peláez, A.J.Rodríguez, S.Terradellas, E.Basart, S.García, R.D.García, O.E.Alonso-Pérez, S.Dust--adverse effectsSahara--ClimateSaharan dustNorth African Dipole Intensity (NAFDI)Saharan Heat Low (SHL)Deserts--Àfrica del NordSàharaÀrees temàtiques de la UPC::EnergiesIt was previously shown that during August the export of Saharan dust to the Atlantic was strongly affected by the difference of the 700-hPa geopotential height anomaly between the subtropics and the tropics over North Africa, which was termed the North African Dipole Intensity (NAFDI). In this work a more comprehensive analysis of the NAFDI is performed, focusing on the entire summer dust season (June–September), and examining the interactions between the mid-latitude Rossby waves (MLRWs) and NAFDI. Widespread and notable aerosol optical depth (AOD) monthly anomalies are found for each NAFDI-phase over the dust corridors off the Sahara, indicating that NAFDI presents intra-seasonal variability and drives dust transport over both the Mediterranean basin and the North Atlantic. Those summer months with the same NAFDI-phase show similar AOD-anomaly patterns. Variations in NAFDI-phase also control the displacement of the Saharan Heat Low (SHL) westwards or eastwards through horizontal advection of temperature over Morocco-Western Sahara or eastern Algeria-Western Libya, respectively. The connection between the SHL and the NAFDI is quantified statistically by introducing two new daily indexes that account for their respective phases (NAFDI daily index -NAFDIDI-, and SHL longitudinal shift index -SHLLSI-) and explained physically using the energy equation of the atmospheric dynamics. The Pearson's correlation coefficient between the one–day-lag SHLLSI and the NAFDIDI for an extended summer season (1980–2013) is 0.78. A positive NAFDI is associated with the West-phase of the SHL, dust sources intensification on central Algeria, and positive AOD anomalies over this region and the Subtropical North Atlantic. A negative NAFDI is associated with the East-phase of the SHL, and positive AOD anomalies over central-eastern Sahara and the central-western Mediterranean Sea. The results point out that the phase changes of NAFDI at intra-seasonal time scale are conducted by those MLRWs that penetrate deeply into the low troposphere.This work is part of the research activities developed by the WMO SDS-WAS Regional Centre for Northern Africa, Middle East and Europe, held by AEMET and BSC-CNS. This study also contributes to Copernicus Atmosphere Monitoring Service (CAMS). Our acknowledgment to ECMWF for providing MACC-dust reanalysis. The authors wish to thank NCEP/NCAR Reanalysis Project. We acknowledge NASA LADS for providing MODIS data. The University of Granada (Spain) and its “Physics and Space Sciences” PhD Programme are acknowledged by A. J. Gómez-Peláez and E. Cuevas. AEROATLAN project (CGL2015-17 66229-P), co-funded by the Ministry of Economy and Competitiveness of Spain and the European Regional Development Fund contributed to this study. Sara Basart acknowledges the CICYT project (CGL2013-46736).Peer ReviewedElsevier20172017-10-0120172017-10-11journal articlehttp://purl.org/coar/resource_type/c_6501AMhttp://purl.org/coar/version/c_ab4af688f83e57aainfo:eu-repo/semantics/articleapplication/pdfhttps://hdl.handle.net/2117/108640https://dx.doi.org/10.1016/j.atmosenv.2017.08.059reponame:UPCommons. Portal del coneixement obert de la UPCinstname:Universitat Politècnica de Catalunya (UPC)Inglésengopen accesshttp://purl.org/coar/access_right/c_abf2Attribution-NonCommercial-NoDerivs 4.0 Spainhttp://creativecommons.org/licenses/by-nc-nd/4.0/es/info:eu-repo/semantics/openAccessoai:upcommons.upc.edu:2117/1086402026-05-27T15:37:01Z
dc.title.none.fl_str_mv The pulsating nature of large-scale Saharan dust transport as a result of interplays between mid-latitude Rossby waves and the North African Dipole Intensity
title The pulsating nature of large-scale Saharan dust transport as a result of interplays between mid-latitude Rossby waves and the North African Dipole Intensity
spellingShingle The pulsating nature of large-scale Saharan dust transport as a result of interplays between mid-latitude Rossby waves and the North African Dipole Intensity
Cuevas, E.
Dust--adverse effects
Sahara--Climate
Saharan dust
North African Dipole Intensity (NAFDI)
Saharan Heat Low (SHL)
Deserts--Àfrica del Nord
Sàhara
Àrees temàtiques de la UPC::Energies
title_short The pulsating nature of large-scale Saharan dust transport as a result of interplays between mid-latitude Rossby waves and the North African Dipole Intensity
title_full The pulsating nature of large-scale Saharan dust transport as a result of interplays between mid-latitude Rossby waves and the North African Dipole Intensity
title_fullStr The pulsating nature of large-scale Saharan dust transport as a result of interplays between mid-latitude Rossby waves and the North African Dipole Intensity
title_full_unstemmed The pulsating nature of large-scale Saharan dust transport as a result of interplays between mid-latitude Rossby waves and the North African Dipole Intensity
title_sort The pulsating nature of large-scale Saharan dust transport as a result of interplays between mid-latitude Rossby waves and the North African Dipole Intensity
dc.creator.none.fl_str_mv Cuevas, E.
Gómez-Peláez, A.J.
Rodríguez, S.
Terradellas, E.
Basart, S.
García, R.D.
García, O.E.
Alonso-Pérez, S.
author Cuevas, E.
author_facet Cuevas, E.
Gómez-Peláez, A.J.
Rodríguez, S.
Terradellas, E.
Basart, S.
García, R.D.
García, O.E.
Alonso-Pérez, S.
author_role author
author2 Gómez-Peláez, A.J.
Rodríguez, S.
Terradellas, E.
Basart, S.
García, R.D.
García, O.E.
Alonso-Pérez, S.
author2_role author
author
author
author
author
author
author
dc.subject.none.fl_str_mv Dust--adverse effects
Sahara--Climate
Saharan dust
North African Dipole Intensity (NAFDI)
Saharan Heat Low (SHL)
Deserts--Àfrica del Nord
Sàhara
Àrees temàtiques de la UPC::Energies
topic Dust--adverse effects
Sahara--Climate
Saharan dust
North African Dipole Intensity (NAFDI)
Saharan Heat Low (SHL)
Deserts--Àfrica del Nord
Sàhara
Àrees temàtiques de la UPC::Energies
description It was previously shown that during August the export of Saharan dust to the Atlantic was strongly affected by the difference of the 700-hPa geopotential height anomaly between the subtropics and the tropics over North Africa, which was termed the North African Dipole Intensity (NAFDI). In this work a more comprehensive analysis of the NAFDI is performed, focusing on the entire summer dust season (June–September), and examining the interactions between the mid-latitude Rossby waves (MLRWs) and NAFDI. Widespread and notable aerosol optical depth (AOD) monthly anomalies are found for each NAFDI-phase over the dust corridors off the Sahara, indicating that NAFDI presents intra-seasonal variability and drives dust transport over both the Mediterranean basin and the North Atlantic. Those summer months with the same NAFDI-phase show similar AOD-anomaly patterns. Variations in NAFDI-phase also control the displacement of the Saharan Heat Low (SHL) westwards or eastwards through horizontal advection of temperature over Morocco-Western Sahara or eastern Algeria-Western Libya, respectively. The connection between the SHL and the NAFDI is quantified statistically by introducing two new daily indexes that account for their respective phases (NAFDI daily index -NAFDIDI-, and SHL longitudinal shift index -SHLLSI-) and explained physically using the energy equation of the atmospheric dynamics. The Pearson's correlation coefficient between the one–day-lag SHLLSI and the NAFDIDI for an extended summer season (1980–2013) is 0.78. A positive NAFDI is associated with the West-phase of the SHL, dust sources intensification on central Algeria, and positive AOD anomalies over this region and the Subtropical North Atlantic. A negative NAFDI is associated with the East-phase of the SHL, and positive AOD anomalies over central-eastern Sahara and the central-western Mediterranean Sea. The results point out that the phase changes of NAFDI at intra-seasonal time scale are conducted by those MLRWs that penetrate deeply into the low troposphere.
publishDate 2017
dc.date.none.fl_str_mv 2017
2017-10-01
2017
2017-10-11
dc.type.none.fl_str_mv journal article
http://purl.org/coar/resource_type/c_6501
AM
http://purl.org/coar/version/c_ab4af688f83e57aa
dc.type.openaire.fl_str_mv info:eu-repo/semantics/article
format article
dc.identifier.none.fl_str_mv https://hdl.handle.net/2117/108640
https://dx.doi.org/10.1016/j.atmosenv.2017.08.059
url https://hdl.handle.net/2117/108640
https://dx.doi.org/10.1016/j.atmosenv.2017.08.059
dc.language.none.fl_str_mv Inglés
eng
language_invalid_str_mv Inglés
language eng
dc.rights.none.fl_str_mv open access
http://purl.org/coar/access_right/c_abf2
Attribution-NonCommercial-NoDerivs 4.0 Spain
http://creativecommons.org/licenses/by-nc-nd/4.0/es/
dc.rights.openaire.fl_str_mv info:eu-repo/semantics/openAccess
rights_invalid_str_mv open access
http://purl.org/coar/access_right/c_abf2
Attribution-NonCommercial-NoDerivs 4.0 Spain
http://creativecommons.org/licenses/by-nc-nd/4.0/es/
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv Elsevier
publisher.none.fl_str_mv Elsevier
dc.source.none.fl_str_mv reponame:UPCommons. Portal del coneixement obert de la UPC
instname:Universitat Politècnica de Catalunya (UPC)
instname_str Universitat Politècnica de Catalunya (UPC)
reponame_str UPCommons. Portal del coneixement obert de la UPC
collection UPCommons. Portal del coneixement obert de la UPC
repository.name.fl_str_mv
repository.mail.fl_str_mv
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