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Titel |
Processing and validation of refractivity from GRAS radio occultation data |
VerfasserIn |
K. B. Lauritsen, S. Syndergaard, H. Gleisner, M. E. Gorbunov, F. Rubek, M. B. Sørensen, H. Wilhelmsen |
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. 10 ; Nr. 4, no. 10 (2011-10-04), S.2065-2071 |
Datensatznummer |
250002108
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Publikation (Nr.) |
copernicus.org/amt-4-2065-2011.pdf |
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Zusammenfassung |
We discuss the processing of GRAS radio occultation (RO) data done at the
GRAS Satellite Application Facility. The input data consists of operational
near-real time bending angles from December 2010 from the Metop-A satellite
operated by EUMETSAT. The data are processed by an Abel inversion algorithm
in combination with statistical optimization based on a two-parameter fit to
an MSIS climatology. We compare retrieved refractivity to analyses from
ECMWF. It is found that for global averages, the mean differences to ECMWF
analyses are smaller than 0.2% below 30 km (except near the surface), with
standard deviations around 0.5% for altitudes between 8 and 25 km. The
current processing is limited by several factors, which are discussed. In
particular, the penetration depth for rising occultations is generally poor,
which is related to the tracking of the L2 signal. Extrapolation of the
difference between the L1 and L2 signals below the altitude where L2 is lost
is possible and would generally allow deeper penetration of retrieved
refractivity profiles into the lower troposphere. |
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