Dynamical effects of solar heating below the cloud layer in a Venus-like atmosphere

The dynamics of Venus' lower-atmospheric superrotation remain an open issue. In the present study, we investigate the sensitivity of the superrotation to diabatic heating rate below the cloud layer using a simplified GCM. A fully developed superrotation fails to develop in the lower atmosphere under the condition with a fairly low diabatic heating below the cloud layer, as is thought to be realistic. Additional radiative forcing in the lower atmosphere and/or eddy momentum source should be considered to produce lower-atmospheric superrotation. The diabatic heating rate below the cloud layer controls the formation of the multiple superrotation states (slow, fast, and extremely fast superrotations). Small changes in the weak lower-atmospheric heating lead to drastic changes of the middle-and lower-atmospheric superrotation.