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| Titel |
Microphysical properties of Sahara dust collected during the Fennec campaign in 2011 |
| VerfasserIn |
Adriana Rocha Lima, Jose Vanderlei Martins, Martin Todd, Richard Washington, John Marshan, Christopher Allen, Sebastian Engelstaedter, Carolina Cavazos-Guerra |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250072508
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| Zusammenfassung |
| Ground measurements of the atmospheric particles are extremely important in order to
integrate aerial and remote sensing measurements. In situ aerosol filters collection and in situ
measurements of aerosol properties were performed at two locations: Bordj Badj Mokthar in
Algeria (Supersite 1) and Bir Moghrein in Mauritania (Supersite 2) in June 2011, as part of
the Fennec project over the central Sahara.
At Supersite 1 an automatized system consisting of an Aerosol Sampling Station (LASS1)
and an integrated Reflectometer-Nephelometer allowed simultaneous collection of aerosol
particles on Nuclepore filters (coarse and fine mode) and continuous measurement of the
scattering and absorption properties of the aerosol particles. At the Supersite 2 in Mauritania
a second Aerosol Sampling Station (LASS2) was also operational during the Fennec
campaign collecting filters continually.
Filters were sent back to laboratory for a series of analysis to obtain the optical and
microphysical properties of the sampled aerosol particles. Gravimetric analysis of each
individual filter gives the concentration of aerosol particles in μg-m3. Particle size
distribution is obtained by scanning electron microscopy and the spectral reflectance of the
filters from (350-2200nm) is being measured to derive the spectral mass absorption
coefficient and refractive index of the aerosol particles.
Preliminary analyses of Supersite 1 for 463nm, 525nm and 637nm wavelength show single
scattering albedo 0.94, 0.96 and 0.98 respectively. X-Ray Fluorescence analyses of some of
the filters from this location indicate Si, Fe, Al and Ca as the main constituent elements of
these particles. At Supersite 2, it was observed periods of very clean conditions
with concentrations below 10Â μg-m3 (June 6-7, Maritime Phase) and periods of
high dust concentration, with peaks of 70Â μg-m3 (June 20-21, Heat Low Phase).
Scanning electron microscopy analysis show high shape heterogeneity of particles and
also the presence of relatively low density particles aggregates that require further
investigation.
The concluding goal of this research is to combine laboratorial and in situ measurements of
dust concentration and optical properties with analysis obtained from Lidar, Aeronet and
flights data simultaneously measured at these two supersites during the Fennec
campaign. This integration is particularly important in the characterization of local
emission events of dust and transport from dust sources. In addition, it will provide
accurate information of the microphysical properties of dust particles from these
regions. |
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