Superrotation maintained by meridional circulation and waves in venus-like AGCM

Masaru Yamamoto, Masaaki Takahashi

Research output: Contribution to journalArticle

49 Citations (Scopus)

Abstract

Fully developed superrotation - 60 times faster than the planetary rotation (243 days) - is simulated using a Venus-like atmospheric general circulation model (AGCM). The angular momentum of the superrotation is pumped up by the meridional circulation with the help of waves, which accelerate the equatorial zonal flow. The waves generated by solar heating and shear instability play a crucial role in the atmospheric dynamics of the Venusian superrotation. Vertical and horizontal momentum transports of thermal tides maintain the equatorial superrotation in the middle atmosphere, while equatorward eddy momentum flux due to shear instability raises the efficiency of upward angular momentum transport by the meridional circulation in the lower atmosphere. In addition to the superrotation, some waves simulated in the cloud layer are consistent with the observations. The planetary-scale Kelvin wave identified as the near-infrared (NIR) oscillation with periods of 5-6 days is generated by the shear instability near the cloud base, and the temperature structure of the diurnal tide is similar to the infrared (IR) observation near the cloud top. Sensitivities to the bottom boundary conditions are also examined in this paper, since the surface physical processes are still unknown. The decrease of the equator-pole temperature difference and the increase of the surface frictional time constant result in the weaknesses of the meridional circulation and superrotation. In the cases of the weak superrotation, the vertical angular momentum transport due to the meridional circulation is inefficient and the equatorward eddy angular momentum transport is absent near 60-km altitude.

Original languageEnglish
Pages (from-to)3296-3314
Number of pages19
JournalJournal of the Atmospheric Sciences
Volume63
Issue number12
DOIs
Publication statusPublished - Dec 1 2006

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meridional circulation
atmospheric general circulation model
Venus
angular momentum
momentum
eddy
tide
planetary rotation
atmospheric dynamics
zonal flow
Kelvin wave
middle atmosphere
near infrared
boundary condition
temperature
oscillation
atmosphere

All Science Journal Classification (ASJC) codes

  • Atmospheric Science

Cite this

Superrotation maintained by meridional circulation and waves in venus-like AGCM. / Yamamoto, Masaru; Takahashi, Masaaki.

In: Journal of the Atmospheric Sciences, Vol. 63, No. 12, 01.12.2006, p. 3296-3314.

Research output: Contribution to journalArticle

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