This is a major release. New Features: Incorporation of ARM-diags which uses in-situ measurements from DOE's ARM (Atmospheric Radiation Measurement) to compare with point grid model output. Diagnostics added include: seasonal mean, annual cycle cycle of a set of atmospheric variables, including (surface temperature, precipitation, radiation fluxes, surface turbulent fluxes...); diurnal cycle of precipitation and cloud; convection onset metrics. MERRA 2 datasets are updated to include monthly main daily maximum and minimum surface air temperature. Other major enhancement Add a test suite for E3SM-Diags on Chrysalis/Anvil Image comparison tests added in unit tests and a complete run Integrate GitHub Actions CI/CD workflow Add and apply formatters and linters to codebase Minor enhancement Code repo clean up by moving test data to E3SM data server and providing data download script. Simplify Conda environments Documentation Include quick guide for Chrysalis/Anvil Update post-processing and run scripts examples Update development guide