Long-term variation in the cloud-tracked zonal velocities at the cloud top of Venus deduced from Venus Express VMC images
Article first published online: 30 JAN 2013
©2012. American Geophysical Union. All Rights Reserved.
Journal of Geophysical Research: Planets
Volume 118, Issue 1, pages 37–46, January 2013
How to Cite
2013), Long-term variation in the cloud-tracked zonal velocities at the cloud top of Venus deduced from Venus Express VMC images, J. Geophys. Res. Planets, 118, 37–46, doi:10.1029/2011JE004013., , , , and (
- Issue published online: 4 MAR 2013
- Article first published online: 30 JAN 2013
- Manuscript Accepted: 9 NOV 2012
- Manuscript Revised: 1 NOV 2012
- Manuscript Received: 24 OCT 2011
- atmosphere dynamics;
 We present observational evidence of the variation of the cloud-tracked zonal velocity by ~20 m s–1 with a timescale of a few hundred days in the southern low latitude region based on an analysis of cloud images taken by the Venus Monitoring Camera on board Venus Express. A spectral analysis suggests that the variation has a periodicity with a period of about 255 days. Although cloud features are not always passive tracers, the periodical variation of the dynamical state is a robust feature. Superposed on this long-term variation of the zonal velocity, Kelvin wave-like disturbances tend to be observed in periods of relatively slow background velocity, while Rossby wave-like disturbances tend to be observed in periods of fast background velocity. Since the momentum deposition by these waves can accelerate and decelerate the mean flow, these waves may contribute to the suggested long-term oscillation.