Limited observational constraints have been a challenge for understanding the role of aerosol in the Earth system. To ensure model process representations are traceable to real-world features, several new diagnostics containing observational constraints have been developed to evaluate critical processes governing aerosol and aerosol-cloud interactions in E3SM. The open-source Earth System Model Aerosol–Cloud Diagnostics (ESMAC Diags) package includes in situ and remote sensing measurements from aircraft, ship, surface, and satellite platforms at multiple testbed regions around the globe. Lagrangian tools and a contoured frequency by optical depth diagram using multi-sensor satellite observations were developed to evaluate the warm rain processes and the role of aerosols thereof. Direct ARM measurements and satellite retrievals reveal that E3SM exhibits an overly strong increase in cloud optical thickness in response to rising cloud condensation nuclei, attributed to too many simulated sub-adiabatic clouds compared to observations. In this presentation, we will discuss efforts for harmonizing the spatiotemporal scales between model simulations and observations. We will demonstrate how these unique metrics diagnose model deficiencies and advance parameterizations necessary for improving E3SM predictions of aerosol and ACI across scales.