UC Berkeley

Abstract A new paradigm in benchmark absorption‐scattering radiative transfer is presented that enables both the globally averaged and spatially resolved testing of climate model radiation parameterizations in order to uncover persistent sources of biases in the aerosol instantaneous radiative effect (IRE). A proof of concept is demonstrated with the Geophysical Fluid Dynamics Laboratory AM4 and Community Earth System Model 1.2.2 climate models. Instead of prescribing atmospheric conditions and aerosols, as in prior intercomparisons, native snapshots of the atmospheric state and aerosol optical properties from the participating models are used as inputs to an accurate radiation solver to uncover model‐relevant biases. These diagnostic results show that the models' aerosol IRE bias is of the same magnitude as the persistent range cited (~1 W/m 2 ) and also varies spatially and with intrinsic aerosol optical properties. The findings underscore the significance of native model error analysis and its dispositive ability to diagnose global biases, confirming its fundamental value for the Radiative Forcing Model Intercomparison Project. Key Points Line by line model coupled to highly accurate multistream solver determines expected instantaneous aerosol radiative effect globally Instantaneous aerosol radiative effect and radiative parameterization error evaluated for the native properties and grids of two GCMs Error varies spatially and with aerosol optical properties. Global average error of 20% in aerosol absorption seen for one model