A Parametric Study of Superrotation of Venus-like Planets : Effects of Obliquity and Period of Planetary Rotation

Abstract

Effects of obliquity and period of planetary rotation on superrotation are examined using a Venus-like GCM. The cloud-top superrotational wind becomes larger with decreasing the oblique angle (< 60° under the conditions of the planetary rotation periods of 16 and 1 Earth days and < 30° under the condition of 243 Earth days). In the Venus-like simulations (243-day planetary rotation), the sensitivities of the atmospheric circulation to the obliquity are classified into three regimes of the slightly, intermediate, and highly oblique angles. The superrotation increases with the magnitudes of the meridional circulation and equator-pole air temperature difference for the slightly oblique angles, while it does not largely change for the highly oblique angles. In the intermediate oblique angle regime, the superrotation largely increases from 40 to 110 m s^-1 with increasing the equator-pole air temperature difference.