|
|
 |
|
|
Ann. Geophys., 24, 3229-3240, 2006
www.ann-geophys.net/24/3229/2006/
© European Geosciences Union 2006
Mesospheric gravity waves observed near equatorial and low–middle latitude stations: wave characteristics and reverse ray tracing results
C. M. Wrasse1, T. Nakamura2, H. Takahashi1, A. F. Medeiros3, M. J. Taylor4, D. Gobbi1, C. M. Denardini1, J. Fechine1, R. A. Buriti3, A. Salatun5, Suratno5, E. Achmad5, and A. G. Admiranto5
1Instituto Nacional de Pesquisas Espaciais (INPE), C.P. 515, 12245-970, São José dos Campos, Brazil
2Institute for Sustainable Humanosphere (RISH), Kyoto University, Uji, Kyoto, 611-0011, Japan
3Universidade Federal de Campina Grande (UFCG), Av. Aprígio Veloso 882, Bodocongó, 58109-970, Campina Grande, Brazil
4Space Dynamics Laboratory and Physics Department, Logan, UT 84322-4145, USA
5Space Science Center, National Institute of Aeronautics and Space, Jalan Pemuda Persil 1, Rawamangun, 13220, Jakarta, Indonesia
Abstract. Gravity wave signatures were extracted from OH airglow observations using
all-sky CCD imagers at four different stations: Cachoeira Paulista (CP)
(22.7° S, 45° W) and São João do Cariri
(7.4° S, 36.5° W), Brazil; Tanjungsari (TJS)
(6.9° S, 107.9° E), Indonesia and Shigaraki
(34.9° N, 136° E), Japan. The gravity wave parameters
are used as an input in a reverse ray tracing model to study the gravity
wave vertical propagation trajectory and to estimate the wave source region.
Gravity waves observed near the equator showed a shorter period and a larger
phase velocity than those waves observed at low-middle latitudes. The waves
ray traced down into the troposphere showed the largest horizontal
wavelength and phase speed. The ray tracing results also showed that at CP,
Cariri and Shigaraki the majority of the ray paths stopped in the mesosphere
due to the condition of m2<0, while at TJS most of the waves are traced
back into the troposphere. In summer time, most of the back traced waves
have their final position stopped in the mesosphere due to m2<0 or
critical level interactions (|m|→∞), which suggests
the presence of ducting waves and/or waves generated in-situ. In the
troposphere, the possible gravity wave sources are related to
meteorological front activities and cloud convections at CP, while at Cariri
and TJS tropical cloud convections near the equator are the most probable
gravity wave sources. The tropospheric jet stream and the orography are thought
to be the major responsible sources for the waves observed at Shigaraki.
Full Article in PDF (2525 KB) |
|
|
