Towards Understanding Biases in Cloud Radiative Effects Simulated in E3SMv3

This study systematically evaluates clouds and their radiative impacts in the newly released U. S. Department of Energy (DOE)’s Energy Exascale Earth System Model (E3SM) version 3 using both satellite data and the DOE Atmospheric Radiation Measurement (ARM) program’s ground-based measurements. The comparison is done by utilizing the Cloud Feedback Model Intercomparison Project (CFMIP) Observation Simulator Package (COSP) and the ground-based lidar and radar simulator package, the Earth Model Column Collaboratory (EMC^2), to improve the model-observation cloud comparison. The use of detailed ARM cloud observations is to better diagnose the strengths and deficiencies of E3SM through process-level understanding. Compared to its earlier versions, E3SMv3 has significantly updated its atmospheric physical parameterizations including noticeable improvements in representing cloud and convective processes. These include the use of the Predicted Particle Properties (P3) scheme for stratiform clouds to improve the treatment of ice microphysical processes and aerosol-cloud interactions and a more sophisticated two-moment bulk cloud microphysics scheme for the Zhang-McFarlane (ZM) deep convection. In addition, mesoscale heating from organized convection is added on top of the ZM deep convective heating. The interactions of deep convection with its environment are enhanced. Several carefully defined sensitivity tests are conducted by tuning off each of the major changes relevant to clouds and convection to isolate their individual impacts on simulation of clouds. Detailed results will be presented in the meeting.