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| Titel |
Thermal infrared remote sensing of mineral dust over land and ocean: a spectral SVD based retrieval approach for IASI |
| VerfasserIn |
L. Klüser, D. Martynenko, T. Holzer-Popp |
| 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. 5 ; Nr. 4, no. 5 (2011-05-02), S.757-773 |
| Datensatznummer |
250001972
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| Publikation (Nr.) |
 copernicus.org/amt-4-757-2011.pdf |
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| Zusammenfassung |
| From the high spectral resolution thermal infrared observations of the Infrared Atmospheric
Sounding Interferometer (IASI) mineral dust AOD (transferred from thermal infrared to
0.5 μm) is retrieved using a Singular Vector Decomposition of brightness
temperature spectra. As infrared retrieval based on 8–12 μm observations, dust
observation with IASI is independent from solar illumination. Through the linear
combinations of suitable independent singular vectors weighted by their contribution to the
observed signal, and a projection of different a-priori dust spectra on the resulting signal
the dust can be well distinguished from the influence of surface emissivity and gas
absorption. In contrast to lookup-table based single-channel retrievals this method takes
advantage of the spectral shape of dust extinction and surface and atmosphere influence over
the total 8–12 μm window band. Using different a-priori spectra for dust
extinction allows also for an estimation of dust particle size in terms of effective radius
based on the respective dust model size distributions. These dust models are also used for
the transfer of infrared AOD to 0.5 μm.
Four months of IASI observations covering Northern Africa and Arabia are used for
evaluation. Two large scale dust events, one covering the Arabian Peninsula and adjacent
parts of the Indian Ocean, the other over the Atlantic Ocean off the coast of West-Africa,
are analysed and compared with other satellite images. They also show the good suitability
of IASI data for dust observation at day and night. Monthly means derived from IASI
observations represent well the known seasonal cycles of dust activity over Northern Africa
and Arabia. IASI Dust AOD0.5 μm and AERONET coarse mode
AOD0.5 μm are reasonably well (linearly) correlated with
ρ=0.623. Moreover, comparison of time series of AERONET and IASI observations shows
that the evolution of dust events is very well covered by the IASI observations. Rank
correlation between dust effective radius and AERONET Ångström exponent is −0.557
indicating the general capability of (qualitative) dust particle size information being
provided by this method. |
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