Publication Date:
2020-03-05
Description:
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 .
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
Format:
application/pdf
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