The representations of clouds in climate model MRI-ESM2 (Yukimoto et al.
2019, JMSJ) used in CMIP6 simulations are significantly improved from
the previous version MRI-CGCM3 used in CMIP5 simulations. The score of
the spatial pattern of 2m temperature for MRI-ESM2 is better than any of
the 47 CMIP6 models. The score for radiative fluxes at the top of the
atmosphere for MRI-ESM2 is ranked in the top seven models among these
CMIP6 models. We will introduce comprehensively various modifications
related to clouds, which contribute to the dramatically improved cloud
representation, and their main impacts (Kawai et al. 2019, GMD). The
modifications cover various schemes and processes including the cloud
scheme, turbulence scheme, cloud microphysics processes, the interaction
between cloud and convection schemes, resolution issues, cloud radiation
processes, aerosol properties, and numerics. In addition, we would like
to mention what data we used during the model development, how we
evaluated our model, how useful the intercomparison studies were, and
what data we need for further model development.