Energy dispersion in a barotropic atmosphere
Article first published online: 10 SEP 2007
Copyright © 1977 Royal Meteorological Society
Quarterly Journal of the Royal Meteorological Society
Volume 103, Issue 438, pages 553–567, October 1977
How to Cite
Hoskins, B. J., Simmons, A. J. and Andrews, D. G. (1977), Energy dispersion in a barotropic atmosphere. Q.J.R. Meteorol. Soc., 103: 553–567. doi: 10.1002/qj.49710343802
- Issue published online: 10 SEP 2007
- Article first published online: 10 SEP 2007
- Manuscript Revised: 24 FEB 1977
- Manuscript Received: 8 DEC 1976
The propagation of energy on the sphere as described by the linear barotropic vorticity equation is studied. For simple flows, the concept of group velocity is examined. Planetary-scale vorticity anomalies exhibit a surprising lack of dispersion in a hemispheric domain. On the sphere, there is more dispersion and a significant cross-equatorial propagation of energy. Planetary-scale vorticity sources tend to produce an orderly downstream train of waves which exhibit a strong tilt (NE-SW for sources in the northern hemisphere) and cross the equator. Zonally elongated sources produce an almost north-south train of waves. For realistic zonal flows with equatorial easterlies, large-scale transients cross the equator, but the long-term forced response in the opposite hemisphere is small.
Comparison of the results with observations of atmospheric wave behaviour is made, and some possible implications are presented.