[A-AS05] Large-scale moisture and organized cloud systems

[AAS05-11] The relationship between convective self-aggregation and cloud vertical mass flux distribution in cloud-resolving simulations

*Takuya Jinno¹, Hiroaki Miura¹ (1.Graduate School of Science, The University of Tokyo)

Keywords:radiative-convective equilibrium, convective self-aggregation

Studying the statistical characteristics of cumulus convection in an equilibrium atmosphere provides a theoretical basis for cumulus parameterization, especially when incorporating stochastic properties. In this study, 3-D radiative-convective equilibrium simulations are performed using a cloud-resolving model, and the frequency distributions of convective vertical mass flux over a wide range of model domain sizes and uniform sea surface temperatures are compared. In experiments where convection cells are spatially random, the distribution function of the mass flux of individual convection cells can be approximated as an exponential distribution. This feature supports the theory of previous studies derived from the analogy with the kinetics for ideal gases. On the other hand, in the experiments with large domain size and high sea surface temperature, where convection and moisture spontaneously form clusters (convective self-aggregation [CSA]), the mass flux distributions deviate strongly from exponential. This feature indicates that the large-scale atmospheric circulation of CSA and the local interaction between clouds affect the statistical properties of the convective cells. We also investigate the effect of prescribed sea surface temperature on various physical processes which contribute to CSA such as radiative heating and lateral entrainment.