Aerosol optical properties in the Arctic: The role of aerosol chemistry and dust composition in a closure experiment between Lidar and tethered balloon vertical profiles

A closure experiment was conducted over Svalbard by comparing Lidar measurements and optical aerosol properties calculated from aerosol vertical profiles measured using a tethered balloon. Arctic Haze was present together with Icelandic dust. Chemical analysis of filter samples, aerosol size distrib...

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Bibliographic Details
Published in:The Science of the total environment 2019-10, Vol.686, p.452-467
Main Authors: Ferrero, L., Ritter, C., Cappelletti, D., Moroni, B., Močnik, G., Mazzola, M., Lupi, A., Becagli, S., Traversi, R., Cataldi, M., Neuber, R., Vitale, V., Bolzacchini, E.
Format: Article
Language:English
Subjects:
Aerosol
Back scattering
Chemical composition
Icelandic dust
Lidar
Optical properties
Svalbard
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Summary:A closure experiment was conducted over Svalbard by comparing Lidar measurements and optical aerosol properties calculated from aerosol vertical profiles measured using a tethered balloon. Arctic Haze was present together with Icelandic dust. Chemical analysis of filter samples, aerosol size distribution and a full set of meteorological parameters were determined at ground. Moreover, scanning electron microscopy coupled with energy-dispersive X-ray (SEM-EDS) data were at disposal showing the presence of several mineralogical phases (i.e., sheet silicates, gypsum, quartz, rutile, hematite). The closure experiment was set up by calculating the backscattering coefficients from tethered balloon data and comparing them with the corresponding lidar profiles. This was preformed in three subsequent steps aimed at determining the importance of a complete aerosol speciation: (i) a simple, columnar refractive index was obtained by the closest Aerosol Robotic Network (AERONET) station, (ii) the role of water-soluble components, elemental carbon and organic matter (EC/OM) was addressed, (iii) the dust composition was included. When considering the AERONET data, or only the ionic water-soluble components and the EC/OM fraction, results showed an underestimation of the backscattering lidar signal up to 76, 53 and 45% (355, 532 and 1064 nm). Instead, when the dust contribution was included, the underestimation disappeared and the vertically-averaged, backscattering coefficients (1.45 ± 0.30, 0.69 ± 0.15 and 0.34 ± 0.08 Mm−1 sr−1, at 355, 532 and 1064 nm) were found in keeping with the lidar ones (1.60 ± 0.22, 0.75 ± 0.16 and 0.31 ± 0.08 Mm−1 sr−1). Final results were characterized by low RMSE (0.36, 0.08 and 0.04 Mm−1 sr−1) and a high linear correlation (R2 of 0.992, 0.992 and 0.994) with slopes close to one (1.368, 0.931 and 0.977, respectively). This work highlighted the importance of all the aerosol components and of the synergy between single particle and bulk chemical analysis for the optical property characterization in the Arctic. [Display omitted] •Lidar and tethered balloon-based aerosol vertical profiles were measured concurrently in the Arctic.•Aerosol chemistry and size distribution were measured during the campaign.•SEM-EDS analyses of dust transport were included in the study.•The refractive index was determined from full chemical composition.•Closure between lidar and balloon-based optical profiles was performed with Mie calculations.
ISSN:0048-9697
1879-1026
DOI:10.1016/j.scitotenv.2019.05.399