Improved treatment of clouds and convection for the DOE Energy Exascale Earth System Model (E3SM) atmospheric model version 3

The treatment of clouds and convection is improved for the version 3 of U.S. Department of Energy's Energy Exascale Earth System Model (E3SM). The Predicted Particle Properties (P3) scheme is now used to handle cloud microphysical processes and improve the treatment of ice. A more sophisticated cloud microphysics scheme is used for convective clouds in the Zhang-McFarlane (ZM) deep convection scheme. A modification is made to the ZM scheme to make it sensitive to large-scale circulation. Mesoscale convective heating is added on top of the deep convective heating from ZM. The impacts of the new physics in atmosphere-only, SST-forced experiments are discussed.

The new model configuration leads to a notable improvement in the representation of variability in the model, while maintaining the good representation of the mean-state climate that already exists in E3SMv2. In terms of the tropical variability, the new configuration has an improved representation of the Madden Julian Oscillation, Kelvin waves, and inertial gravity waves. The phase and amplitude of the diurnal cycle of precipitation across many land and oceanic regions are also improved. More details will be presented in the meeting.