Open AccessQuasiperiodic southward moving waves in 630‐nm airglow images in the equatorial thermosphere
Author(s) -
Shiokawa K.,
Otsuka Y.,
Ogawa T.
Publication year - 2006
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2005ja011406
Subject(s) - airglow , thermosphere , quasiperiodic function , geology , earth's magnetic field , ionosphere , geophysics , equator , latitude , atmospheric sciences , gravity wave , gravitational wave , geodesy , physics , astrophysics , magnetic field , quantum mechanics , condensed matter physics
We report quasiperiodic southward moving waves, which are commonly observed in the OI 630‐nm airglow images (emission altitudes of 200–300 km) near the equator, in 2‐year airglow observations at Kototabang, Indonesia (0.2°S, 100.3°E, geomagnetic latitude of −10.4°). The waves have predominantly east‐west phase fronts and repeatedly propagate southward with a velocity of 310 ± 110 m/s and a period of 40 ± 15 min. They are frequently observed in May–July with an occurrence rate of 53% and are also observed in other seasons with occurrences of ∼20%. The waves are observed in and to the south (geomagnetically poleward) of the equatorial ionospheric anomaly, which is identified as an airglow enhancement region moving gradually to lower geomagnetic latitudes at the premidnight local times. We suggest that gravity waves in the lower thermosphere below ∼300 km are a plausible cause of the observed quasiperiodic waves in the airglow images.