Two dimensional numerical experiments of atmospheric convection with condensation of the major component

In Martian atmosphere, atmospheric major component, CO2, condenses. CO2 ice clouds are formed in current Martian polar regions (Pettengill and Ford, 2000). It is discussed that CO2 ice clouds cause warm climate in early Mars (Forget and Pierrehumbert, 1997: Mitsuda, 2007). It is pointed out that supersaturation can influence significantly CO2 cloud structure for convection with condensation of major component (Colaprete et al., 2003). Laboratory experiments and observations suggest the emergence of super saturated regions in Martian atmosphere(Glandorf et al., 2002). Colaprete et al. (2003) discusses that high convective clouds which reach near tropopause does not develop but only thin clouds emerges the condensation level for the case that supersaturation is inhibited. In this case, temperature of ascent region must be equal to that of descent region, and air parcel can not obtain buoyancy due to degeneracy of degrees of freedom for thermodynamic variables. Colaprete et al. (2003) also shows that active cloud convection can occur if highly supersaturation is permitted in CO2 atmosphere. However, Colaprete et al. (2003) uses vertical one dimensional model in which convective motion is parameterized. Cloud convection model should be used in order to investigate cloud structure with condensation of major component, since cloud distribution is affected greatly by distribution of ascent and descent regions. We have been developing cloud convection model in order to investigate atmospheric convective structure in various planets (e.g., Nakajima et al, 2000: Odaka et al., 2006: Sugiyama et al., 2009). Odaka et al. (2006) incorporates the effects of condensation of major component into the cloud convection model, and perform numerical experiments of ascending thermal plume as a test calculation. In this paper, we improve condensation process in the model of Odaka et al. (2006), and perform long time integration in order to investigate flow field and cloud distribution in statistical equilibrium states with considering supersaturation.