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| Titel |
Potential for the use of reconstructed IASI radiances in the detection of atmospheric trace gases |
| VerfasserIn |
N. C. Atkinson, F. I. Hilton, S. M. Illingworth, J. R. Eyre, T. Hultberg |
| 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 ; 3, no. 4 ; Nr. 3, no. 4 (2010-07-30), S.991-1003 |
| Datensatznummer |
250001214
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| Publikation (Nr.) |
 copernicus.org/amt-3-991-2010.pdf |
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| Zusammenfassung |
Principal component (PC) analysis has received considerable attention as a
technique for the extraction of meteorological signals from hyperspectral
infra-red sounders such as the Infrared Atmospheric Sounding Interferometer
(IASI) and the Atmospheric Infrared Sounder (AIRS). In addition to achieving
substantial bit-volume reductions for dissemination purposes, the technique
can also be used to generate reconstructed radiances in which random
instrument noise has been reduced. Studies on PC analysis of hyperspectral
infrared sounder data have been undertaken in the context of numerical
weather prediction, instrument monitoring and geophysical variable
retrieval, as well as data compression. This study examines the potential of
PC analysis for chemistry applications.
A major concern in the use of PC analysis for chemistry is that the spectral
features associated with trace gases may not be well represented in the
reconstructed spectra, either due to deficiencies in the training set or due
to the limited number of PC scores used in the radiance reconstruction. In
this paper we show examples of reconstructed IASI radiances for several
trace gases: ammonia, sulphur dioxide, methane and carbon monoxide. It is
shown that care must be taken in the selection of spectra for the initial
training set: an iterative technique, in which outlier spectra are added to
a base training set, gives the best results. For the four trace gases
examined, key features of the chemical signatures are retained in the
reconstructed radiances, whilst achieving a substantial reduction in
instrument noise.
A new regional re-transmission service for IASI is scheduled to start in
2010, as part of the EUMETSAT Advanced Retransmission Service (EARS). For
this EARS-IASI service it is intended to include PC scores as part of the
data stream. The paper describes the generation of the reference
eigenvectors for this new service. |
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