How a mesoscale cyclonic vortex over Sahara leads to a dust outbreak in South-western Iberia

Couto, Flavio T.; Cardoso, Eduardo; Costa, María João; Salgado, Rui; Guerrero-Rascado, Juan Luís; Salgueiro, Vanda

doi:10.1016/j.atmosres.2020.105302

Cited by 11 publications

(9 citation statements)

References 64 publications

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“…Smoke particles from nearby wildfires or industrialized regions are regularly transported over the station (Preißler et al, 2013;Pereira et al, 2014), and it also receives long-range-transported smoke from North America (Sicard et al, 2019;Baars et al, 2019). Furthermore, due to the station's proximity to the Sahara Desert, mineral dust layers are frequent over the city (Pereira et al, 2009;Preißler et al, 2011Preißler et al, , 2013 with many extreme events occurring (Preißler et al, 2011;Valenzuela et al, 2017;Couto et al, 2021). Rare events of simultaneous biomass burning and mineral dust intrusions have been characterized (Salgueiro et al, 2021).…”

Section: Actris/earlinet Stationsmentioning

confidence: 99%

Statistical validation of Aeolus L2A particle backscatter coefficient retrievals over ACTRIS/EARLINET stations on the Iberian Peninsula

et al. 2022

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Abstract. The Global Observing System (GOS) has encountered some limitations due to a lack of worldwide real-time wind measurements. In this context, the European Space Agency (ESA) has developed the Aeolus satellite mission, based on the ALADIN (Atmospheric Laser Doppler Instrument) Doppler wind lidar; this mission aims to obtain near-real-time wind retrievals at the global scale. As spin-off products, the instrument retrieves aerosol optical properties such as particle backscatter and extinction coefficients. In this work, a validation of Aeolus reprocessed (baseline 10) co-polar backscatter coefficients (βAeoluspart) is presented through an intercomparison with analogous ground-based measurements taken at the ACTRIS (Aerosols, Clouds and Trace gases Research InfraStructure Network)/EARLINET (European Aerosol Research Lidar Network) stations of Granada (Spain), Évora (Portugal) and Barcelona (Spain) over the period from July 2019 until October 2020. Case studies are first presented, followed by a statistical analysis. The stations are located in a hot spot between Africa and the rest of Europe, which guarantees a variety of aerosol types, from mineral dust layers to continental/anthropogenic aerosol, and allows us to test Aeolus performance under different scenarios. The so called Aeolus-like profiles (βAeoluslike,355part) are obtained from total particle backscatter coefficient and linear particle depolarization ratio (δlinearpart) profiles at 355 and 532 nm measured from the surface, through a thorough bibliographic review of dual-polarization measurements for relevant aerosol types. Finally, the study proposes a relation for the spectral conversion of δlinearpart, which is implemented in the Aeolus-like profile calculation. The statistical results show the ability of the satellite to detect and characterize significant aerosol layers under cloud-free conditions, along with the surface effect on the lowermost measurements, which causes the satellite to largely overestimate co-polar backscatter coefficients. Finally, the Aeolus standard correct algorithm middle bin (SCAmb) shows a better agreement with ground-based measurements than the standard correct algorithm (SCA), which tends to retrieve negative and meaningless coefficients in the clear troposphere. The implementation of Aeolus quality flags entails a vast reduction in the number of measurements available for comparison, which affects the statistical significance of the results.

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Section: Actris/earlinet Stationsmentioning

confidence: 99%

Statistical validation of Aeolus L2A particle backscatter coefficient retrievals over ACTRIS/EARLINET stations on the Iberian Peninsula

et al. 2022

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“…The meteorological situation is described by using the NCEP/NCAR reanalysis data to check the conditions favouring the advection injection of Saharan dust over the IP (Salvador et al, 2014;Díaz et al, 2017;Couto et al, 2021). On the one hand, the meteorological scenarios are described by using daily pictures of geopotential height composite mean at 700 hPa (around 3000 m a.s.l.)…”

Section: Synoptic Scenariomentioning

confidence: 99%

“…Saharan dust can be transported to Europe under certain meteorological conditions (e.g. Salvador et al, 2014;Marinou et al, 2017;Russo et al, 2020;Couto et al, 2021), occasionally reaching rather high altitudes (up to 8 km height; e.g. Mona et al, 2006;Papayannis et al, 2008;Córdoba-Jabonero et al, 2021a;Sicard et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

Vertical characterization of fine and coarse dust particles during an intense Saharan dust outbreak over the Iberian Peninsula in springtime 2021

López-Cayuela¹,

Córdoba-Jabonero

Bermejo-Pantaleón

et al. 2023

Atmos. Chem. Phys.

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Abstract. An intense and long-lasting Saharan dust outbreak crossed the Iberian Peninsula (IP) from the southwest (SW) to the northeast (NE) from 25 March until 7 April 2021. This work aims to assess the optical and mass contribution of both fine and coarse dust particles along their transport. Five Iberian lidar stations were monitoring the transport and evolution of the Saharan dust particles, i.e. El Arenosillo/Huelva, Granada, Torrejón/Madrid and Barcelona in Spain, and Évora in Portugal. The particular meteorological conditions determined the aerosol scenario along the overall dust event, differing in the first part of the event (25–31 March), in which the strongest dust incidence occurred on 29–31 March at the south and central stations and 1 April at Barcelona, from the second one (1–7 April). The use of the two-step POLIPHON algorithm showed the relevance of using polarized lidar measurements for separating the aerosol properties of dust fine and coarse particles as an added value. Both the fine dust (Df) and coarse dust (Dc) components of the total particle backscatter coefficient (total dust, DD = Dc + Df) were separately derived. The dust plume was well-mixed with height and no significant differences were found in the vertical structure of both the Dc and Df particle backscatter coefficients. From the beginning of the dust outbreak until 1 April, the vertical Df / DD mass ratio was nearly constant in time at each station and also in altitude with values of ∼ 10 %. Moreover, the mean dust optical depth at 532 nm was decreasing along that dust pathway, reporting values from SW to NE stations of 0.34 at El Arenosillo/Huelva, 0.28 at Granada, 0.20 at Évora, 0.28 at Torrejón/Madrid, and 0.14 at Barcelona, although its Df / DD ratio remained almost constant (28 %–30 %). A similar pattern was found for the total dust mass loading and its Df / DD ratio, i.e. mostly decreasing mean mass values were reported, being constant in its Df / DD ratio (∼ 10 %) along the SW–NE dust pathway. In addition, the episode-mean centre-of-mass height increased with latitude overall, showing a high variability, being greater than 0.5 km at the southern sites (El Arenosillo/Huelva, Granada, Évora) and ∼ 1.0 km at Torrejón/Madrid and Barcelona. However, despite the relatively high intensity of the dust intrusion, the expected ageing of the dust particles was hardly observed, by taking into account the minor changes found in the contribution and properties of the coarse and fine dust particles. This is on the basis that the IP is relatively close to the Saharan dust sources and then, under certain dust transport conditions, any potential ageing processes in the dust particles remained unappreciated. The following must be highlighted: the different relative contribution of the fine dust particles to the total dust found for their optical properties (∼ 30 %) associated with the radiative effect of dust, with respect to that for the mass features (∼ 10 %) linked to air quality issues, along the overall dust event by crossing the IP.

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“…Smoke particles from nearby wildfires or industrialized regions are regularly transported over the station (Preißler et al, 2013;Pereira et al, 2014), as well as long-range transport from North America (Sicard et al, 2019;Baars et al, 2019). Furthermore, due to the proximity to the Sahara Desert, mineral dust layers are frequent over the city (Pereira et al, 2009;Preißler et al 2011Preißler et al , 2013 with many extreme events (Preißler et al, 2011;Valenzuela et al, 2017;Couto et al, 2021). Rare events of simultaneous biomass burnings and mineral dust intrusions have been characterized (Salgueiro et al, 2021).…”

Section: Actris/earlinet Stationsmentioning

confidence: 99%

Statistical validation of Aeolus L2A particle backscatter coefficient retrievals over ACTRIS/EARLINET stations in the Iberian Peninsula

Abril-Gago

Guerrero-Rascado

Costa

et al. 2021

Preprint

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Abstract. Global Observing Systems (GOS) encounter some limitations due to a lack of worldwide real-time wind measurements. In this context, the European Space Agency (ESA) has developed the Aeolus satellite mission, based on the ALADIN (Atmospheric Laser Doppler Instrument) Doppler wind lidar, aimed to obtain near real-time wind retrievals at global scale. As spin-off products, the instrument retrieves aerosol optical properties such as particle backscatter and extinction coefficients. In this work, a validation of Aeolus reprocessed (baseline 10) co-polar backscatter coefficients is presented through an intercomparison with analogous ground-based measurements taken at the ACTRIS/EARLINET stations of Granada (Spain), Évora (Portugal) and Barcelona (Spain) over the period from July 2019 until October 2020. Case studies are first presented, followed by a statistical analysis. The stations are located in a hot spot between Africa and the rest of Europe, which guarantees a variety of aerosol types, from mineral dust layers to continental/anthropogenic aerosol, and allow us to test Aeolus performance under different scenarios. The so called Aeolus-like profiles are obtained from total particle backscatter coefficient and linear particle depolarization ratio profiles at 355 nm and 532 nm measured from surface, through a thorough bibliographic review of dual-polarization measurements for relevant aerosol types. Finally, the study proposes a relation for the spectral conversion of , which is implemented in the Aeolus-like profile calculation. The statistical results show the ability of the satellite to detect and characterize significant aerosol layers under cloud free conditions, along with the surface effect on the lowermost measurements, which causes the satellite to largely overestimate co-polar backscatter coefficients. Finally, Aeolus standard correct algorithm middle bin (SCAmb) shows a better agreement with ground-based measurements than the standard correct algorithm (SCA), which tends to retrieve negative and meaningless coefficients in the clear troposphere. The implementation of Aeolus quality flags entails a vast reduction in the number of measurements available for comparison, which affects the statistical significance of the results, without improving significantly the statistical agreement between satellite and ground-based measurements.

show abstract

How a mesoscale cyclonic vortex over Sahara leads to a dust outbreak in South-western Iberia

Cited by 11 publications

References 64 publications

Statistical validation of Aeolus L2A particle backscatter coefficient retrievals over ACTRIS/EARLINET stations on the Iberian Peninsula

Statistical validation of Aeolus L2A particle backscatter coefficient retrievals over ACTRIS/EARLINET stations on the Iberian Peninsula

Vertical characterization of fine and coarse dust particles during an intense Saharan dust outbreak over the Iberian Peninsula in springtime 2021

Statistical validation of Aeolus L2A particle backscatter coefficient retrievals over ACTRIS/EARLINET stations in the Iberian Peninsula

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