K. Shiokawa et al., Multi-point observation of short-period mesospheric gravity waves over Japan during the FRONT campaign, GEOPHYS R L, 27(24), 2000, pp. 4057-4060
Simultaneous observations of short-period gravity waves were carried out us
ing three all-sky cooled-CCD imagers of OH airglow at Moshiri (northern edg
e of Japan) and at Shigaraki and Bisei (middle part of Japan) during the FR
ONT campaign of May 1998. These stations were separated by horizontal dista
nces of 250 - 1300 km, and they offered a unique opportunity to investigate
the spatial extent of gravity waves in the mesopause region. The images fr
om Shigaraki and Bisei showed short-period gravity waves (horizontal wavele
ngth: 20-40 km, phase front: similar to east-west aligned) moving northward
(phase velocity: 20-40 m/s) on May 19, 21 and 22. At Moshiri, similar east
-west waves moving northward were observed on May 19 and 21, indicating a b
road horizontal extent of the gravity waves. Waves at Moshiri were not evid
ent on May 22, however. The horizontal wind measured by the MF radar at Wak
kanai (near Moshiri) showed height profiles that were similar to those at Y
amagawa (southern edge of Japan) on May 10 and 21 but quite dissimilar oil
May 22. On the basis of these data, we suggest that short-period gravity wa
ves in the mesopause region carl have a I,road spatial extent of more than
1000 km. The generation and propagation of internal gravity waves are discu
ssed as a cause of the spatial extent of thc waves.