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| Titel |
First Odin sub-mm retrievals in the tropical upper troposphere: ice cloud properties |
| VerfasserIn |
P. Eriksson, M. Ekström, B. Rydberg, D. P. Murtagh |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 7, no. 2 ; Nr. 7, no. 2 (2007-01-25), S.471-483 |
| Datensatznummer |
250004472
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| Publikation (Nr.) |
 copernicus.org/acp-7-471-2007.pdf |
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| Zusammenfassung |
| More accurate global measurements of the amount of ice in thicker
clouds are needed to validate atmospheric models and sub-mm
radiometry can be an important component in this respect. A cloud
ice retrieval scheme for the first such instrument in space,
Odin-SMR, is presented here. Several advantages of sub-mm
observations are shown, such as low influence of particle shape and
orientation, and a high dynamic range of the retrievals. In the case
of Odin-SMR, only cloud ice above ≈12.5 km can be
measured. The present retrieval scheme gives a detection threshold
of about 4 g/m2 above 12.5 km and does not saturate even
for thickest observed clouds (>500 g/m2). The main
retrieval uncertainties are the assumed particle size distribution
and cloud inhomogeneity effects. The overall retrieval accuracy is
estimated to be ~75%. The retrieval error is judged to have
large random components and to be significantly lower than this value
for averaged results, but high fixed errors can not be excluded.
However, a firm lower value can always be provided. Initial results
are found to be consistent with similar Aura MLS retrievals, but
show important differences to corresponding data from atmospheric
models. This first retrieval algorithm is limited to lowermost
Odin-SMR tangent altitudes, and further development should improve
the detection threshold and the vertical resolution. It should also
be possible to decrease the retrieval uncertainty associated with
cloud inhomogeneities by detailed analysis of other data sets. |
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