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| Titel |
Retrieval of aerosol optical depth over land surfaces from AVHRR data |
| VerfasserIn |
L. L. Mei, Y. Xue, A. A. Kokhanovsky, W. von Hoyningen-Huene, G. de Leeuw, 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 ; 7, no. 8 ; Nr. 7, no. 8 (2014-08-08), S.2411-2420 |
| Datensatznummer |
250115865
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| Publikation (Nr.) |
 copernicus.org/amt-7-2411-2014.pdf |
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| Zusammenfassung |
| The Advanced Very High Resolution Radiometer (AVHRR) provides a global,
long-term, consistent time series of radiance data in several wavebands which
are used for the retrieval of surface spectral reflectance, albedo and
surface temperature. Long-term time series of such data products are
necessary for studies addressing climate change, sea ice distribution and
movement, and ice sheet coastal configuration. AVHRR radiances have also been
used to retrieve aerosol properties over ocean and land surfaces. However,
the retrieval of aerosol over land is challenging because of the limited
information content in the data which renders the inversion problem ill
defined. Solving the radiative transfer equations requires additional
information to reduce the number of unknowns. In this contribution we utilise
an empirical linear relationship between the surface reflectances in the
AVHRR channels at wavelengths of 3.75 μm and 2.1 μm,
which has been identified in the Moderate Resolution Imaging
Spectroradiometer (MODIS) data. Following the MODIS dark target approach,
this relationship is used to obtain the surface reflectance at
0.64 μm. The comparison of the estimated surface reflectances with
MODIS reflectance products (MOD09) shows a strong correlation. Once this was
established, the MODIS "dark-target" aerosol retrieval method was adapted
to AVHRR data. A simplified look-up table (LUT) method, adopted from the
Bremen AErosol Retrieval (BAER) algorithm, was used in the retrieval. The
aerosol optical depth (AOD) values retrieved from AVHRR with this method
compare favourably with ground-based measurements, with 71.8% of the
points located within ±(0.1 + 0.15τ) (τ is the AOD) of the
identity line. This method can be easily applied to other satellite
instruments which do not have a 2.1 μm channel, such as those
currently planned to be used on geostationary satellites. |
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