Simulations of superrotation using a GCM for Venus’ middle atmosphere
© The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences. 2007
Received: 20 October 2006
Accepted: 25 April 2007
Published: 31 August 2007
A superrotation is simulated in a T10L100 general circulation model for Venus’ middle atmosphere (VMAGCM), in which the radiative effects of aerosols are calculated. The simulation in a domain of 30–100 km is conducted under the condition of a bottom zonal flow with a velocity of 50 m s−1 at the equator. Thermal tides contribute to the maintenance of the cloud-top superrotation together with meridional circulation and vertically propagating gravity waves. The meridional circulation and wave activity are sensitive to the vertical eddy diffusion. Although the equatorial zonal flow has a velocity of about 70 m s−1 when the vertical eddy diffusion coefficient (KV) is set at 5.0 m s−2, it has a velocity of <100 m s−1 when KV = 2.5 m s−2. The fully developed equatorial jet for the small KV case is enhanced at 65 km by small-scale gravity waves emitted from the cloud top.