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| Titel |
Inter-calibration of polar imager solar channels using SEVIRI |
| VerfasserIn |
J. F. Meirink, R. A. Roebeling, P. Stammes |
| 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 ; 6, no. 9 ; Nr. 6, no. 9 (2013-09-26), S.2495-2508 |
| Datensatznummer |
250085070
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| Publikation (Nr.) |
 copernicus.org/amt-6-2495-2013.pdf |
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| Zusammenfassung |
| Accurate calibration of satellite imagers is a prerequisite for using their
measurements in climate applications. Here we present a method for the
inter-calibration of geostationary and polar-orbiting imager solar channels
based on regressions of collocated near-nadir reflectances. Specific
attention is paid to correcting for differences in spectral response between
instruments. The method is used to calibrate the solar channels of the
Spinning Enhanced Visible and Infrared Imager (SEVIRI) on the geostationary
Meteosat satellite with corresponding channels of the Moderate Resolution
Imaging Spectroradiometer (MODIS) on the polar-orbiting Aqua satellite. The
SEVIRI operational calibration is found to be stable during the years 2004 to
2009, but offset by −8, −6, and +3.5 % for channels 1
(0.6 μm), 2 (0.8 μm), and 3 (1.6 μm),
respectively. These results are robust for a range of choices that can be
made regarding data collocation and selection, as long as the viewing and
illumination geometries of the two instruments are matched. Uncertainties in
the inter-calibration method are estimated to be 1 % for channel 1 and
1.5 % for channels 2 and 3. A specific application of our method is the
inter-calibration of polar imagers using SEVIRI as a transfer instrument.
This offers an alternative to direct inter-calibration, which in general has
to rely on high-latitude collocations. Using this method we have tied
MODIS-Terra and Advanced Very High Resolution Radiometer (AVHRR) instruments
on National Oceanic and Atmospheric Administration (NOAA) satellites 17 and
18 to MODIS-Aqua for the years 2007 to 2009. While reflectances of the two
MODIS instruments differ less than 2 % for all channels considered,
deviations of an existing AVHRR calibration from MODIS-Aqua reach −3.5 and
+2.5 % for the 0.8 and 1.6 μm channels, respectively. |
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