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| Titel |
Aircraft measurements of gravity waves in the upper troposphere and lower stratosphere during the START08 field experiment |
| VerfasserIn |
Fuqing Zhang, Junhong Wei, Meng Zhang, K. P. Bowman, L. L. Pan, E. Atlas, S. C. Wofsy |
| 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 ; 15, no. 13 ; Nr. 15, no. 13 (2015-07-14), S.7667-7684 |
| Datensatznummer |
250119894
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| Publikation (Nr.) |
 copernicus.org/acp-15-7667-2015.pdf |
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| Zusammenfassung |
| This study analyzes in situ airborne measurements from the 2008
Stratosphere–Troposphere Analyses of Regional Transport (START08) experiment
to characterize gravity waves in the extratropical upper troposphere and
lower stratosphere (ExUTLS). The focus is on the second research flight
(RF02), which took place on 21–22 April 2008. This was the first airborne
mission dedicated to probing gravity waves associated with strong
upper-tropospheric jet–front systems. Based on spectral and wavelet analyses
of the in situ observations, along with a diagnosis of the polarization
relationships, clear signals of mesoscale variations with wavelengths
~ 50–500 km are found in almost every segment of the 8 h
flight, which took place mostly in the lower stratosphere. The aircraft
sampled a wide range of background conditions including the region near the
jet core, the jet exit and over the Rocky Mountains with clear evidence of
vertically propagating gravity waves of along-track wavelength between 100
and 120 km. The power spectra of the horizontal velocity components and
potential temperature for the scale approximately between ~ 8 and ~ 256 km display an approximate −5/3 power law in
agreement with past studies on aircraft measurements, while the fluctuations
roll over to a −3 power law for the scale approximately between
~ 0.5 and ~ 8 km (except when this part of
the spectrum is activated, as recorded clearly by one of the flight
segments). However, at least part of the high-frequency signals with sampled
periods of ~ 20–~ 60 s and wavelengths of
~ 5–~ 15 km might be due to intrinsic
observational errors in the aircraft measurements, even though the
possibilities that these fluctuations may be due to other physical phenomena
(e.g., nonlinear dynamics, shear instability and/or turbulence) cannot be
completely ruled out. |
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