Transport of desert dust mixed with North African industrial pollutants in the subtropical Saharan Air Layer

Rodrı́guez, Sergio; Alastuey, Andrés; Alonso-Pérez, Silvia; Querol, Xavier; Cuevas, E.; Abreu-Afonso, J.; Viana, Mar; Pérez, Noemí; Pandolfi, M.; Rosa, J. de la

doi:10.5194/acp-11-6663-2011

Cited by 260 publications

(252 citation statements)

References 75 publications

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“…Table 1 shows the composition of the aerosol samples collected at Izaña. Concentrations of aerosol major components are the same as those found in previous studies (Maring et al., 2000; Rodríguez et al, 2011). All species present much higher concentrations within the SAL than within the WES.…”

Section: Resultssupporting

confidence: 77%

“…Elemental composition was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES, IRIS Advantage TJA Solutions, THERMO ™ ) and inductively coupled plasma mass spectrometry (ICP-MS, X Series II, THERMO ™ ) after acid digestion of the sample. Mineral dust was calculated as the sum of Al 2 O 3 + SiO 2 + Fe + CaCO 3 + K + Na + Mg + P + Ti + Sr (see details in Rodríguez et al, 2011Rodríguez et al, , 2015 and normalized so Al accounts for 8 % of the dust mass (see details in Pérez García-Pando et al, 2016). SO = 4 was split into non-sea-salt sulfate (nss-SO = 4 ) and sea salt sulfate (nss-SO = 4 = SO = 4 − ss-SO = 4 ) based on the relation between marine Na and SO = 4 .…”

Section: Inorganicsmentioning

confidence: 99%

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Speciation of organic aerosols in the Saharan Air Layer and in the free troposphere westerlies

García¹,

Drooge²,

Rodrı́guez³

et al. 2017

Atmos. Chem. Phys.

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Abstract. We focused this research on the composition of the organic aerosols transported in the two main airflows of the subtropical North Atlantic free troposphere: (i) the Saharan Air Layer -the warm, dry and dusty airstream that expands from North Africa to the Americas at subtropical and tropical latitudes -and (ii) the westerlies, which flow from North America over the North Atlantic at mid-and subtropical latitudes. We determined the inorganic compounds (secondary inorganic species and elemental composition), elemental carbon and the organic fraction (bulk organic carbon and organic speciation) present in the aerosol collected at Izaña Observatory, ∼ 2400 m a.s.l. on the island of Tenerife. The concentrations of all inorganic and almost all organic compounds were higher in the Saharan Air Layer than in the westerlies, with bulk organic matter concentrations within the range 0.02-4.0 µg m −3 . In the Saharan Air Layer, the total aerosol population was by far dominated by dust (93 % of bulk mass), which was mixed with secondary inorganic pollutants (< 5 %) and organic matter (∼ 1.5 %). The chemical speciation of the organic aerosols (levoglucosan, dicarboxylic acids, saccharides, n-alkanes, hopanes, polycyclic aromatic hydrocarbons and those formed after oxidation of α-pinene and isoprene, determined by gas chromatography coupled with mass spectrometry) accounted for 15 % of the bulk organic matter (determined by the thermooptical transmission technique); the most abundant organic compounds were saccharides (associated with surface soils), secondary organic aerosols linked to oxidation of biogenic isoprene (SOA ISO) and dicarboxylic acids (linked to several primary sources and SOA). When the Saharan Air Layer shifted southward, Izaña was within the westerlies stream and organic matter accounted for ∼ 28 % of the bulk mass of aerosols. In the westerlies, the organic aerosol species determined accounted for 64 % of the bulk organic matter, with SOA ISO and dicarboxylic acids being the most abundant; the highest concentration of organic matter (3.6 µg m −3 ) and of some organic species (e.g. levoglucosan and some dicarboxylic acids) were associated with biomass burning linked to a fire in North America. In the Saharan Air Layer, the correlation found between SOA ISO and nitrate suggests a large-scale impact of enhancement of the formation rate of secondary organic aerosols due to interaction with anthropogenic NO x emissions.

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Section: Resultssupporting

confidence: 77%

Section: Inorganicsmentioning

confidence: 99%

Speciation of organic aerosols in the Saharan Air Layer and in the free troposphere westerlies

García¹,

Drooge²,

Rodrı́guez³

et al. 2017

Atmos. Chem. Phys.

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“…In addition, the summertime FT of the northern subtropical Atlantic is frequently affected by air masses that are advected from the African continent (e.g. Prospero et al, 2002;Rodríguez et al, 2011;Andrey et al, 2014). At that time of the year there are strong and extended heat lows over the African continent at 20-35 • N. These heat lows modify the transport pathways to the FT and enable mixing from the PBL to the FT (e.g.…”

Section: Dehydration Via Condensation Versus Vertical Mixing From Thementioning

confidence: 99%

“…The Izaña programme for in situ aerosol characterization was audited by the World Calibration Centre for Aerosol Physics (WCCAP; Institute for Tropospheric Research, Leipzig) in November 2006. For more details on these PM 10 data please refer to Rodríguez et al (2011).…”

Section: Appendix B: the Aerosol Data Setsmentioning

confidence: 99%

“…13, which shows that at Izaña and in summer high aerosol concentrations (PM 10 > 25 µg m −3 ) are clearly correlated to air masses that have been advected from the African continent. The PM 10 aerosol data show the aerosol mass concentration considering all particles with aerodynamic diameter smaller than 10 µm, and at Izaña, PM 10 is, by far, dominated by Saharan dust particles (Rodríguez et al, 2011). For the calculation of the backward trajectories we use HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory -some examples and explanations of the HYSPLIT calculations are given in Cuevas et al, 2013).…”

Section: Aerosol Data As Proxy For Transport Pathwaysmentioning

confidence: 99%

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Empirical validation and proof of added value of MUSICA's tropospheric δD remote sensing products

et al. 2015

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Abstract. The project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water) integrates tropospheric water vapour isotopologue remote sensing and in situ observations. This paper presents a first empirical validation of MUSICA's H 2 O and δD remote sensing products, generated from groundbased FTIR (Fourier transform infrared), spectrometer and space-based IASI (infrared atmospheric sounding interferometer) observation. The study is made in the area of the Canary Islands in the subtropical northern Atlantic. As reference we use well calibrated in situ measurements made aboard an aircraft (between 200 and 6800 m a.s.l.) by the dedicated ISOWAT instrument and on the island of Tenerife at two different altitudes (at Izaña, 2370 m a.s.l., and at Teide, 3550 m a.s.l.) by two commercial Picarro L2120-i water isotopologue analysers.The comparison to the ISOWAT profile measurements shows that the remote sensors can well capture the variations in the water vapour isotopologues, and the scatter with respect to the in situ references suggests a δD random uncertainty for the FTIR product of much better than 45 ‰ in the lower troposphere and of about 15 ‰ for the middle troposphere. For the middle tropospheric IASI δD product the study suggests a respective uncertainty of about 15 ‰. In both remote sensing data sets we find a positive δD bias of 30-70 ‰.Complementing H 2 O observations with δD data allows moisture transport studies that are not possible with H 2 O observations alone. We are able to qualitatively demonstrate the added value of the MUSICA δD remote sensing data. We document that the δD-H 2 O curves obtained from the different in situ and remote sensing data sets (ISOWAT, Picarro at Izaña and Teide, FTIR, and IASI) consistently identify two different moisture transport pathways to the subtropical north eastern Atlantic free troposphere.

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Solar radiation measurements compared to simulations at the BSRN Izaña station. Mineral dust radiative forcing and efficiency study

García

Cuevas

et al. 2014

JGR Atmospheres

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[1] This paper presents a comparative study of shortwave downward radiation (SDR) measurements and simulations, obtained with the radiative transfer model LibRadtran, at the Baseline Surface Radiation Network (BSRN) site of Izaña Atmospheric Observatory (IZA, Spain). The analysis is based on cloud-free days between March 2009 and August 2012 (386 days), including aerosol-free and Saharan mostly pure mineral dust conditions and comparing the day-to-day, annual, and interannual variability. The observed agreement between simulations and measurements is excellent: the variance of daily measurements overall agrees within 99% with the variance of daily simulations, and the mean bias (simulations-measurements) is -0.30˙0.24 MJm -2 (-1.1˙0.9%) for global, -0.16˙0.34 MJm -2 (-0.4˙0.9%) for direct, and +0.02˙0.25 MJm -2 (+0.9˙9.2%) for diffuse SDR. Furthermore, the diurnally averaged aerosol radiative forcing (DF) and radiative forcing efficiency (DF eff ) due to Saharan mostly pure mineral dust events has been computed at Izaña Observatory. The mean DF values are -7˙1, -96˙5, and 44˙2 Wm -2 for global, direct, and diffuse BSRN SDR, respectively (mean aerosol optical depth, AOD, at 500 nm of 0.18˙0.01), whereas the mean DF eff values are -59˙6, -495˙11, and 230˙8 Wm -2 per unit of AOD at 500 nm for global, direct, and diffuse BSRN SDR, respectively. These values highlight the importance of scattering processes for mineral dust aerosols: the ratio between DF and the corresponding SDR without aerosols is 2.5% for diffuse SDR versus 0.2% for direct SDR. This illustrates the significant potential of mineral dust particles to cool the Earth-atmosphere system.

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Transport of desert dust mixed with North African industrial pollutants in the subtropical Saharan Air Layer

Cited by 260 publications

References 75 publications

Speciation of organic aerosols in the Saharan Air Layer and in the free troposphere westerlies

Speciation of organic aerosols in the Saharan Air Layer and in the free troposphere westerlies

Empirical validation and proof of added value of MUSICA's tropospheric δD remote sensing products

Solar radiation measurements compared to simulations at the BSRN Izaña station. Mineral dust radiative forcing and efficiency study

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