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| Titel |
The benefit of limb cloud imaging for infrared limb sounding of tropospheric trace gases |
| VerfasserIn |
S. Adams, R. Spang, P. Preusse, G. Heinemann |
| 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 ; 2, no. 1 ; Nr. 2, no. 1 (2009-06-22), S.287-298 |
| Datensatznummer |
250000444
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| Publikation (Nr.) |
 copernicus.org/amt-2-287-2009.pdf |
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| Zusammenfassung |
| Advances in detector technology enable a new generation of infrared limb
sounders to measure 2-D images of the atmosphere. A proposed limb cloud
imager (LCI) mode will detect clouds with a spatial resolution unprecedented
for limb sounding. For the inference of temperature and trace gas
distributions, detector pixels of the LCI have to be combined into
super-pixels which provide the required signal-to-noise and information
content for the retrievals. This study examines the extent to which
tropospheric coverage can be improved in comparison to limb sounding using a
fixed field of view with the size of the super-pixels, as in conventional
limb sounders. The study is based on cloud topographies derived from (a) IR
brightness temperatures (BT) of geostationary weather satellites in
conjunction with ECMWF temperature profiles and (b) ice and liquid water
content data of the Consortium for Small-scale Modeling-Europe (COSMO-EU) of
the German Weather Service. Limb cloud images are simulated by matching the
cloud topography with the limb sounding line of sight (LOS). The analysis of
the BT data shows that the reduction of the spatial sampling along the track
has hardly any effect on the gain in information. The comparison between BT
and COSMO-EU data identifies the strength of both data sets, which are the
representation of the horizontal cloud extent for the BT data and the
reproduction of the cloud amount for the COSMO-EU data. The results of the
analysis of both data sets show the great advantage of the cloud imager.
However, because both cloud data sets do not present the complete fine
structure of the real cloud fields in the atmosphere it is assumed that the
results tend to underestimate the increase in information. In conclusion,
real measurements by such an instrument may result in an even higher benefit
for tropospheric limb retrievals. |
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