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| Titel |
Comparing ECMWF AOD with AERONET observations at visible and UV wavelengths |
| VerfasserIn |
V. Cesnulyte, A. V. Lindfors, M. R. A. Pitkänen, K. E. J. Lehtinen, J.-J. Morcrette, A. Arola |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 2 ; Nr. 14, no. 2 (2014-01-21), S.593-608 |
| Datensatznummer |
250118294
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| Publikation (Nr.) |
 copernicus.org/acp-14-593-2014.pdf |
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| Zusammenfassung |
| This paper presents validation results of the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecasting
System MACC (Monitoring Atmospheric Composition and Climate) re-analysis aerosol optical depth (AOD) for the period 2003–2006.
We evaluate the MACC AOD at a UV wavelength (340 nm) and at
mid-visible (500 and 550 nm) by comparing against ground-based AERONET
measurements at 12 sites. The AERONET sites cover various parts of the globe
and are categorized in three groups: urban/anthropogenic, biomass burning
and dust, depending on the typically dominating aerosol type. This is the
first time a global model such as the ECMWF has been evaluated for the
performance of AOD at a UV wavelength. The results show that the MACC system
generally provides a good representation of the AOD on a monthly basis,
showing a realistic seasonal cycle. The model is mostly able to capture
major dust load events and also the peak months of biomass burning
correctly. For Kanpur and Solar Village, however, the model overestimates
the AOD during the monsoon period when the aerosol load is generally low.
When comparing hourly AOD values, the model–measurement agreement is better
for biomass burning and dust sites than for urban sites, with an average
correlation coefficient around 0.90 for biomass burning sites, around 0.77
for dust sites, and below 0.70 for urban sites. The AOD at 500 nm averaged
over all sites shows only a small systematic difference between modeled and
measured values, with a relative mean bias of 0.02. However, for the AOD at
340 nm the relative mean bias is −0.2. All sites included in the study show
a relative mean bias at 340 nm smaller (or more negative) than that at 500 nm, indicating a strong wavelength dependence in the performance of the AOD
in the MACC system. A comparison against fine and coarse mode AOD of the
AERONET indicates that this has to do with the size distribution of the
model: generally, the ECMWF model overestimates the contribution by coarse
mode particles. |
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