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Size distribution and optical properties of mineral dust aerosols transported in the western Mediterranean

Denjean, C ; Cassola, F ; Mazzino, A ; Triquet, S ; Chevaillier, S ; Grand, N ; Bourrianne, T ; Momboisse, G ; Sellegri, K ; Schwarzenbock, A ; Freney, E ; Mallet, M ; menti, P

Atmospheric chemistry and physics, 2016-02, Vol.16 (2), p.1081-1104 [Periódico revisado por pares]

Katlenburg-Lindau: Copernicus GmbH

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Título:
Size distribution and optical properties of mineral dust aerosols transported in the western Mediterranean
Autor: Denjean, C ; Cassola, F ; Mazzino, A ; Triquet, S ; Chevaillier, S ; Grand, N ; Bourrianne, T ; Momboisse, G ; Sellegri, K ; Schwarzenbock, A ; Freney, E ; Mallet, M ; menti, P
Assuntos: Absorption ; Aerodynamics ; Aerosol effects ; Aerosol optical properties ; Aerosols ; Air pollution ; Aircraft ; Aircraft components ; Albedo ; Albedo (solar) ; Atmospheric and Oceanic Physics ; Atmospheric heating ; Atmospheric models ; Atmospheric particulates ; Atmospheric transport ; Black carbon ; Boundary layers ; Chemical composition ; Chemical pollution ; Climate ; Cloud formation ; Computer simulation ; Depletion ; Dimming ; Dust ; Dust effects ; Dust plumes ; Dust storms ; Electromagnetic absorption ; Gravitation ; Gravity ; Heating ; Height ; Light absorption ; Marine aerosols ; Marine pollution ; Mediterranean climate ; Modelling ; Optical properties ; Particle size distribution ; Particulates ; Physics ; Plumes ; Pollution ; Pollution abatement ; Pollution dispersion ; Radiative transfer ; Rain ; Rainfall ; Rainfall patterns ; Regional climates ; Regions ; Satellites ; Scattering ; Sea level ; Size distribution ; Sulfate particles ; Sulfates ; Transport ; Turbulence ; Vertical profiles ; Vertical turbulence
É parte de: Atmospheric chemistry and physics, 2016-02, Vol.16 (2), p.1081-1104
Descrição: This study presents in situ aircraft measurements of Saharan mineral dust transported over the western Mediterranean basin in June–July 2013 during the ChArMEx/ADRIMED (the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region) airborne campaign. Dust events differing in terms of source region (Algeria, Tunisia and Morocco), time of transport (1–5 days) and height of transport were sampled. Mineral dust were transported above the marine boundary layer, which conversely was dominated by pollution and marine aerosols. The dust vertical structure was extremely variable and characterized by either a single layer or a more complex and stratified structure with layers originating from different source regions. Mixing of mineral dust with pollution particles was observed depending on the height of transport of the dust layers. Dust layers carried a higher concentration of pollution particles below 3 km above sea level (a.s.l.) than above 3 km a.s.l., resulting in a scattering Ångström exponent up to 2.2 below 3 km a.s.l. However, the optical properties of the dust plumes remained practically unchanged with respect to values previously measured over source regions, regardless of the altitude. Moderate absorption of light by the dust plumes was observed with values of aerosol single scattering albedo at 530 nm ranging from 0.90 to 1.00. Concurrent calculations from the aerosol chemical composition revealed a negligible contribution of pollution particles to the absorption properties of the dust plumes that was due to a low contribution of refractory black carbon in regards to the fraction of dust and sulfate particles. This suggests that, even in the presence of moderate pollution, likely a persistent feature in the Mediterranean, the optical properties of the dust plumes could be assumed similar to those of native dust in radiative transfer simulations, modelling studies and satellite retrievals over the Mediterranean. Measurements also showed that the coarse mode of mineral dust was conserved even after 5 days of transport in the Mediterranean, which contrasts with the gravitational depletion of large particles observed during the transport of dust plumes over the Atlantic. Simulations with the WRF mesoscale meteorological model highlighted a strong vertical turbulence within the dust layers that could prevent deposition of large particles during their atmospheric transport. This has important implications for the dust radiative effects due to surface dimming, atmospheric heating and cloud formation. The results presented here add to the observational data set necessary for evaluating the role of mineral dust on the regional climate and rainfall patterns in the western Mediterranean basin and understanding their atmospheric transport at global scale.
Editor: Katlenburg-Lindau: Copernicus GmbH
Idioma: Inglês

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Size distribution and optical properties of mineral dust aerosols transported in the western Mediterranean

Denjean, C ; Cassola, F ; Mazzino, A ; Triquet, S ; Chevaillier, S ; Grand, N ; Bourrianne, T ; Momboisse, G ; Sellegri, K ; Schwarzenbock, A ; Freney, E ; Mallet, M ; menti, P

Katlenburg-Lindau: Copernicus GmbH

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