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Titel |
An evaluation of COSMIC radio occultation data in the lower atmosphere over the Southern Ocean |
VerfasserIn |
L. B. Hande, S. T. Siems, M. J. Manton, D. H. Lenschow |
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 ; 8, no. 1 ; Nr. 8, no. 1 (2015-01-09), S.97-107 |
Datensatznummer |
250116041
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Publikation (Nr.) |
copernicus.org/amt-8-97-2015.pdf |
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Zusammenfassung |
The global positioning system (GPS) radio occultation (RO) method is a
relatively new technique for taking atmospheric measurements for use in both
weather and climate studies. As such, this technique needs to be evaluated
for all parts of the globe. Here, we present an extensive evaluation of the
performance of the Constellation Observing System for Meteorology,
Ionosphere, and Climate (COSMIC) GPS RO observations of the Southern Ocean
boundary layer. The two COSMIC products used here are the "wetPrf" product,
which is based on 1-D variational analysis with European Centre for
Medium-Range Weather Forecasts (ECMWF), and the "atmPrf" product, which
contains the raw measurements from COSMIC. A direct comparison of temporally
and spatially co-located COSMIC profiles and high resolution radiosonde
profiles from Macquarie Island (54.62° S, 158.85° E)
highlights weaknesses in the ability of both COSMIC products to identify the
boundary layer structure, as identified by break points in the refractivity
profile. In terms of reproducing the temperature and moisture profile in the
lowest 2.5 km, the "wetPrf" COSMIC product does not perform as well as an
analysis product from the ECMWF. A further statistical analysis is performed
on a large number of COSMIC profiles in a region surrounding Macquarie
Island. This indicates that, statistically, COSMIC performs well at capturing
the heights of main and secondary break points. However, the frequency of
break points detected is lower than the radiosonde profiles suggest, but this
could be simply due to the long horizontal averaging in the COSMIC
measurements. There is also a weak seasonal cycle in the boundary layer
height similar to that observed in the radiosonde data, providing some
confidence in the ability of COSMIC to detect an important boundary layer
variable. |
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