From its inception, the Energy Exascale Earth System Model (E3SM) was meant to be a high-resolution climate model. For phase 1 of the project, this meant coupled simulations with a grid resolution of 25 km for the land and atmosphere and 8-16 km for ocean and sea ice. A 50 yr control simulation with this model demonstrated that model climate is very stable and has a skill comparable to other world-class CMIP models. Tropical cyclones are simulated realistically and orographic precipitation is improved relative to lower-resolution runs. In phase 2 of the project, the E3SM atmosphere model is being rewritten to operate as a global cloud-resolving model (with a target grid spacing of 3 km). This new version of the model will explicitly resolve large eddies in both the ocean and the atmosphere, enabling a whole new realm of coupled modeling studies. In order to make a 3 km global atmosphere model tractable, intense focus is being placed on making each atmospheric process as simple, efficient, and scalable as possible. Early results from this effort will be presented.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. It is supported by the Energy Exascale Earth System Model (E3SM) project, funded by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research. IM Release LLNL-ABS-754943.