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Long‐term variation in the cloud‐tracked zonal velocities at the cloud top of Venus deduced from Venus Express VMC images
Author(s) -
Kouyama Toru,
Imamura Takeshi,
Nakamura Masato,
Satoh Takehiko,
Futaana Yoshifumi
Publication year - 2013
Publication title -
journal of geophysical research: planets
Language(s) - English
Resource type - Journals
eISSN - 2169-9100
pISSN - 2169-9097
DOI - 10.1029/2011je004013
Subject(s) - venus , rossby wave , variation (astronomy) , zonal flow (plasma) , geology , latitude , oscillation (cell signaling) , kelvin wave , cloud computing , geophysics , climatology , atmospheric sciences , geodesy , physics , astronomy , astrobiology , quantum mechanics , plasma , biology , computer science , tokamak , genetics , operating system
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.