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| Titel |
Evaluation of operational forecast model of aerosol transportation using ceilometer network measurements |
| VerfasserIn |
Ka Lok Chan, Matthias Wiegner, Harald Flentje, Ina Mattis, Frank Wagner, Josef Gasteiger, Alexander Geiß |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250141651
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| Publikation (Nr.) |
 EGU/EGU2017-5185.pdf |
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| Zusammenfassung |
| Due to technical improvements of ceilometers in recent years, ceilometer measurements are
not only limited to determine cloud base heights but also providing information on the
vertical aerosol distribution. Therefore, several national weather services implemented
ceilometer networks. These measurements are e.g. valuable for the evaluation of the chemical
transport model simulations.
In this study, we present comparisons of European Centre for Medium-Range Weather
Forecast Integrated Forecast System (ECMWF-IFS) model simulation of aerosol
backscatter coefficients with ceilometer network measurements operated by the
German weather service (DWD) . Five different types of aerosol are available in the
model simulations which include two natural aerosols, sea salt and dust. The other
three aerosol types, i.e. sulfate, organic carbon and black carbon, have significant
anthropogenic contributions. As the model output provides mass mixing ratios
of the above mentioned types of aerosol and the ceilometers measure attenuated
backscatter (β∗) provided that calibration took place, it is necessary to determine a
common physical quantity for the comparison. We have chosen the aerosol backscatter
coefficient (β) for this purpose. The β-profiles are calculated from the mass mixing
ratios of the model output assuming the inherent aerosol microphysics properties. It
shall be emphasized that in the model calculations, all particles are assumed to be
spherical.
We have examined the sensitivity of the intercomparison on the hygroscopic growth of
particles and on the role of particle shape. Our results show that the hygroscopic growth of
particle is crucial (up to a factor of 22) in converting the model output to backscatter
coefficient profiles whereas the effect of non-sphericity of dust particles is comparably small
(∼44%). Furthermore, the calibration of the ceilometer signals can be an issue. The
agreements between modeled and retrieved β-profiles show different characteristic
in terms of absolute values and in the height of the mixing layer under different
circumstances. |
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