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| Titel |
Retrieval of spectral aerosol optical thickness over land using ocean color sensors MERIS and SeaWiFS |
| VerfasserIn |
W. Hoyningen-Huene, J. Yoon, M. Vountas, L. G. Istomina, G. Rohen, T. Dinter, A. A. Kokhanovsky, J. P. Burrows |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 4, no. 2 ; Nr. 4, no. 2 (2011-02-03), S.151-171 |
| Datensatznummer |
250001668
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| Publikation (Nr.) |
 copernicus.org/amt-4-151-2011.pdf |
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| Zusammenfassung |
| For the determination of aerosol optical thickness (AOT) Bremen
AErosol Retrieval (BAER) has been developed. Method and main
features on the aerosol retrieval are described together with
validation and results. The retrieval separates the spectral
aerosol reflectance from surface and Rayleigh path reflectance for
the shortwave range of the measured spectrum of top-of-atmosphere
reflectance for wavelength less than 0.670 μm. The
advantage of MERIS (Medium Resolution Imaging Spectrometer on the
Environmental Satellite – ENVISAT – of the European Space Agency
– ESA) and SeaWiFS (Sea viewing Wide Field Sensor on OrbView-2
spacecraft) observations is the availability of several spectral
channels in the blue and visible range enabling the spectral
determination of AOT in 7 (or 6) channels
(0.412–0.670 μm) and additionally channels in the NIR,
which can be used to characterize the surface properties. A
dynamical spectral surface reflectance model for different surface
types is used to obtain the spectral surface reflectance for this
separation. The normalized differential vegetation index (NDVI),
taken from the satellite observations, is the model input. Further
surface bi-directional reflectance distribution function (BRDF) is
considered by the Raman-Pinty-Verstraete (RPV) model. Spectral AOT
is obtained from aerosol reflectance using look-up-tables,
obtained from radiative transfer calculations with given aerosol
phase functions and single scattering albedos either from aerosol
models, given by model package "optical properties of aerosol
components" (OPAC) or from experimental campaigns. Validations of
the obtained AOT retrieval results with data of Aerosol Robotic
Network (AERONET) over Europe gave a preference for experimental
phase functions derived from almucantar measurements. Finally
long-term observations of SeaWiFS have been investigated for 11
year trends in AOT. Western European regions have negative trends
with decreasing AOT with time. For the investigated Asian region
increasing AOT have been found. |
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