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| Titel |
Inversion of GPS meteorology data |
| VerfasserIn |
K. Hocke |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 15, no. 4 ; Nr. 15, no. 4, S.443-450 |
| Datensatznummer |
250012730
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| Publikation (Nr.) |
 copernicus.org/angeo-15-443-1997.pdf |
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| Zusammenfassung |
| The GPS meteorology (GPS/MET) experiment, led
by the Universities Corporation for Atmospheric Research (UCAR), consists of a
GPS receiver aboard a low earth orbit (LEO) satellite which was launched on 3
April 1995. During a radio occultation the LEO satellite rises or sets relative
to one of the 24 GPS satellites at the Earth's horizon. Thereby the atmospheric
layers are successively sounded by radio waves which propagate from the GPS
satellite to the LEO satellite. From the observed phase path increases, which
are due to refraction of the radio waves by the ionosphere and the neutral
atmosphere, the atmospheric parameter refractivity, density, pressure and
temperature are calculated with high accuracy and resolution (0.5–1.5 km). In
the present study, practical aspects of the GPS/MET data analysis are discussed.
The retrieval is based on the Abelian integral inversion of the atmospheric
bending angle profile into the refractivity index profile. The problem of the
upper boundary condition of the Abelian integral is described by examples. The
statistical optimization approach which is applied to the data above 40 km and
the use of topside bending angle profiles from model atmospheres stabilize the
inversion. The retrieved temperature profiles are compared with corresponding
profiles which have already been calculated by scientists of UCAR and Jet
Propulsion Laboratory (JPL), using Abelian integral inversion too. The
comparison shows that in some cases large differences occur (5 K and more). This
is probably due to different treatment of the upper boundary condition, data
runaways and noise. Several temperature profiles with wavelike structures at
tropospheric and stratospheric heights are shown. While the periodic structures
at upper stratospheric heights could be caused by residual errors of the
ionospheric correction method, the periodic temperature fluctuations at heights
below 30 km are most likely caused by atmospheric waves (vertically propagating
large-scale gravity waves and equatorial waves). |
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