Dynamical Effect on Static Stability of the Venus Atmosphere Simulated Using a General Circulation Model: A Comparison With Radio Occultation Measurements. Issue 3 (23rd March 2022) - Ando, Hiroki
Abstract: 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. Plain Language Summary: The thermal structure of the Venus atmosphere, namely distributions of temperature and static stability, is very important because it represents a degree of atmospheric stratification. Furthermore, it is strongly related to the heat transport due to the atmospheric dynamics such as mean meridional circulation and disturbances. In this study, the temperature and static stability distributions revealed by recent radio occultation measurements were well reproduced by a Venus general circulation model. We examined dynamical effects due to the mean meridional circulation and disturbances on static stability to elucidate how the thermal structures were maintained. At low‐latitudes, the mean meridional circulation and disturbances play an important role in maintaining the static stability distribution. At mid‐ and high‐latitudes, the static stability distribution is strongly affected by planetary‐scale atmospheric waves. In addition, we clarified the characteristics of the waves and proposed their origins. The structures and characteristics of the mean meridional circulation and disturbances shown in this study will help us to investigate how the super‐rotation is maintained in terms of their momentum transport. Key Points: The thermal structure of the Venus atmosphere reproduced with a general circulation model is consistent with recent radio occultation measurements Heat transport due to disturbances strongly affects the thermal structure at mid‐ and high‐latitudes Equatorward heat transport induced by the interaction between Rossby waves produces a deep low‐stability layer in the polar region