Papers on Ionosphere and Upper Atmosphere
Airglow observations of mesoscale low-velocity traveling ionospheric disturbances at midlatitudes
Article first published online: 20 SEP 2012
Copyright 2000 by the American Geophysical Union.
Journal of Geophysical Research: Space Physics (1978–2012)
Volume 105, Issue A8, pages 18407–18415, 1 August 2000
How to Cite
2000), Airglow observations of mesoscale low-velocity traveling ionospheric disturbances at midlatitudes, J. Geophys. Res., 105(A8), 18407–18415, doi:10.1029/1999JA000305., , , and (
- Issue published online: 20 SEP 2012
- Article first published online: 20 SEP 2012
- Manuscript Accepted: 3 APR 2000
- Manuscript Received: 23 AUG 1999
This paper presents a summary of 630.0 nm emission observations made by the Cornell All-Sky Imager that have revealed an abundance of structure in the midlatitude thermosphère. Some events were so bright that the weaker 557.7 nm thermospheric line was readily visible and produced sharper images because of the shorter excitation lifetime. Global Positioning System observations show that the airglow features are traveling ionospheric disturbances (TIDs). The remarkable feature of the data is the overwhelming tendency for these low-velocity TIDs to develop with a northwest to southeast orientation and to propagate in the southwest direction. Speeds ranged from 50 to 170 m/s, and wavelengths ranged from 50 to 500 km. The Perkins instability is investigated as a possible explanation for the structures. The linear theory, including both winds and electric fields, predicts a positive but small growth rate. However, the real part of the dispersion relation gives the wrong sign for the wave propagation. Furthermore, the growth rate seems too small to amplify a seed gravity wave significantly during one period of neutral gas oscillation. We conclude that this class of low-velocity TID is not yet explained theoretically.