 |
| Titel |
Studies of gravity wave propagation in the mesosphere observed by MU radar |
| VerfasserIn |
H. Y. Lue, F. S. Kuo, S. Fukao, T. Nakamura |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
0992-7689
|
| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 31, no. 5 ; Nr. 31, no. 5 (2013-05-15), S.845-858 |
| Datensatznummer |
250019038
|
| Publikation (Nr.) |
 copernicus.org/angeo-31-845-2013.pdf |
|
|
|
|
|
| Zusammenfassung |
| Mesospheric data were analyzed by a composite method combining phase and
group velocity tracing technique and the spectra method of Stokes parameter
analysis to obtain the propagation parameters of atmospheric gravity waves
(AGW) in the height ranges between 63.6 and 99.3 km, observed using the MU
radar at Shigaraki in Japan in the months of November and July in the years
1986, 1988 and 1989. The data of waves with downward phase velocity and the
data of waves with upward phase velocity were independently treated. First,
the vertical phase velocity and vertical group velocity as well as the
characteristic wave period for each wave packet were obtained by phase and
group velocity tracing technique. Then its horizontal wavelength, intrinsic
wave period and horizontal group velocity were obtained by the dispersion
relation. The intrinsic frequency and azimuth of wave vector of each wave
packet were checked by Stokes parameters analysis. The results showed that
the waves with intrinsic periods in the range
30 min–4.5 h
had horizontal wavelength ranging from 25 to 240 km, vertical wavelength
from 2.5 to 12 km, and horizontal group velocities from 15 to 60 m s−1.
Both upward moving wave packets and downward moving wave packets had
horizontal group velocities mostly directed in the sector between
directions NNE (north-north-east) and SEE in the month of November, and
mostly in the sector between directions NW and SWS in the month of
July. Comparing with mean wind directions, the gravity waves appeared to
be more likely to propagate along with mean wind than against it. This apparent prevalence for downstream wave packets was found to be
caused by a systematic filtering effect existing in the process of phase and
group velocity tracing analysis: A significant portion of upstream wave
packets might have been Doppler shifted out of the vertical range in phase
and group velocity tracing analysis. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|