Convective Self Aggregation and Radiative Convective Equilibrium across the MPI-M model hierarchy

Simulations of radiative convective equilibrium (RCE) have greatly influenced the understanding of climate, and climate change. Early simulations were performed with very simple one-dimensional models of the atmosphere, followed by cloud-resolving simulations. In the last five years it has also become common practice to simulate RCE with comprehensive general circulation models.

These recent studies revealed that different RCE states can be found, depending on how convection aggregates, even in the absence of external asymmetries in the forcing, and have motivated the RCEMIP project, which defines a standardized experimental protocol, to study RCE across a range of models. In this poster we present findings from our investigation of simulations performed — with the full spectrum of models developed and applied at the Max Planck Institute for Meteorology — as a contribution to RCEMIP and the World Climate Research Programmes Grand Challenge on Clouds Circulation and Climate Sensitivity. Our analysis emphasizes how commonalities (or differences) are manifest in the base RCE state, how this base RCE state depends on convective aggregation, how convection self-aggregates, and how these properties respond to warming. Simulations are performed using the UCLA-LES and ICON-LEM models (which resolve shallow clouds but with different microphysics), the cloud-resolving configuration of the ICON-NWP model, along with ECHAM and ICON-A, the atmosphere components of the MPI-ESM and ICON-ESM, respectively. The simulations and their differences are interpreted with the help of KONRAD, a simple one-dimensional model with a relaxed convective adjustment scheme and a simple prescription of cloud properties.