Dynamical effect on the Venusian thermal structure simulated by a general circulation model

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 transport due to the mean meridional circulation is important at low-latitudes. At mid- and high-latitudes, meanwhile, the baroclinic Rossby-type wave plays an important role in maintaining the thermal structure. In addition, appreciable equatorward heat transport is found to maintain the deep and low-stability layer in the polar region, which might be induced by the interaction between the baroclinic Rossby-type wave in the low-stability layer and the trapped Rossby-type wave below it.