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| Titel |
Analysis of vertical wave number spectrum of atmospheric gravity waves in the stratosphere using COSMIC GPS radio occultation data |
| VerfasserIn |
T. Tsuda, X. Lin, H. Hayashi, Noersomadi |
| 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. 8 ; Nr. 4, no. 8 (2011-08-26), S.1627-1636 |
| Datensatznummer |
250002080
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| Publikation (Nr.) |
 copernicus.org/amt-4-1627-2011.pdf |
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| Zusammenfassung |
GPS radio occultation (RO) is characterized by high accuracy and excellent
height resolution, which has great advantages in analyzing atmospheric
structures including small-scale vertical fluctuations. The vertical
resolution of the geometrical optics (GO) method in the stratosphere is
about 1.5 km due to Fresnel radius limitations, but full spectrum inversion
(FSI) can provide superior resolutions. We applied FSI to COSMIC GPS-RO
profiles from ground level up to 30 km altitude, although basic retrieval at
UCAR/CDAAC sets the sewing height from GO to FSI below the tropopause. We
validated FSI temperature profiles with routine high-resolution radiosonde
data in Malaysia and North America collected within 400 km and about 30 min
of the GPS RO events. The average discrepancy at 10–30 km altitude
was less than 0.5 K, and the bias was equivalent with the GO results.
Using the FSI results, we analyzed the vertical wave number spectrum of
normalized temperature fluctuations in the stratosphere at 20–30 km
altitude, which exhibits good consistency with the model spectra of
saturated gravity waves. We investigated the white noise floor that tends to
appear at high wave numbers, and the substantial vertical resolution of the
FSI method was estimated as about 100–200 m in the lower stratosphere. We
also examined a criterion for the upper limit of the FSI profiles, beyond
which bending angle perturbations due to system noises, etc., could exceed
atmospheric excess phase fluctuations. We found that the FSI profiles can be
used up to about 28 km in studies of temperature fluctuations with vertical
wave lengths as short as 0.5 km. |
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