Dynamical Effect on Static Stability of the Venus Atmosphere Simulated Using a General Circulation Model: A Comparison With Radio Occultation Measurements

Distributions of temperature and static stability in the Venus atmosphere consistent with recent radio occultation measurements are reproduced using a general circulation model. A low-stability layer is maintained at low- and mid-latitudes at 50–60 km altitude and is sandwiched by high- and moderate-stability layers extending above 60 and below 50 km, respectively. In the polar region, the low-stability layer is located at 46–63 km altitude and the relatively low-stability layer is also found at 40–46 km altitude. To investigate how these thermal structures form, we examine the dynamical effects of the atmospheric motions on the static stability below 65 km altitude. The results show that the heat transports due to the mean meridional circulation and disturbances are important in low-latitudes. The mid- and high-latitudes above ∼47 km are destabilized by radiative processes and stabilized by the disturbances, which are mainly associated with baroclinic Rossby-type waves. Below ∼47 km altitude, the polar region is destabilized by the dynamical processes which induce the appreciable equatorward heat transport, which might be related to Rossby waves in the sub-cloud region, although the suppression of convective adjustment at cloud heights leads to stabilization at 43–47 km.