Evaluating TaiESM1 Frozen Hydrometeor–Radiation Coupling over Tropical and Subtropical Pacific Oceans Against Observations and CMIP6 Models

TaiESM1 is based on CESM1.2.2 with CAM5 atmosphere, CICE4 sea-ice, CLM4 land surface, and POP2 ocean components. The falling ice radiative effects (FIRE) parameterization in TaiESM1 augments the effective ice optical properties seen by the radiation code by adding the diagnostic snow mixing ratios to the cloud-ice input of the radiation scheme, weighted by appropriate effective-radius relationships for large, polycrystalline ice habits. Two sets of CMIP6-protocol historical simulations (1850–2014) were performed, each initialized from a fully coupled pre-industrial control (piControl) run that was integrated for several hundred years until the global mean top-of-atmosphere energy imbalance reached near-equilibrium (drift < 0.5 W m⁻² yr⁻¹): (1) SON, the standard TaiESM1 submission to CMIP6 that includes FIREs; f09.B-hist.tn15.cmip6.k35.cam.h0-TS-TAUX-TAUY-PREC-2D-1920-2014-CDO_1x1.nc and (2) NOS, an otherwise identical run with FIREs deactivated, f09.B-hist.k32.NOS02.cam.h0-TS-TAUX-TAUY-PREC-2D-1920-2014-CDO_1x1.nc