Sensitivities of simulated global aerosol optical depth and aerosol-radiation interactions to different horizontal resolutions in CAS-FGOALS-f3

The variations of horizontal grid spacing in aerosol climate models lead to discrepancies in simulated aerosol optical properties and radiation effects. To quantitatively investigate the effects of model horizontal resolution on global atmospheric aerosol simulation, the aerosol optical depths (AODs) and aerosol-radiation interactions (ARIs) for 10 years (2005–2014) are simulated by the Chinese Academy of Sciences Flexible Global Ocean Atmosphere Land System (CAS-FGOALS-f3) with a high resolution (HRM, ∼25 km) and a low resolution (LRM, ∼100 km). The experiments are performed with the same model parameterizations except the time step in HRM and LRM to maintain the stability of the dynamical core. The results show that the AODs simulated in HRM are more comparable to the multi-satellites and ground-based retrievals than those in LRM. Upon investigating the aerosol components, the differences in the carbonaceous and sulfate AODs between the HRM and LRM are more than 30%. The resolution sensitivities of hygroscopic aerosol simulations are mainly attributed to the simulated relative humidity (RH) and aerosol wet scavenging. The aerosol transports by wind fields alter the distributions of aerosol. The more reasonable simulations of the meteorological fields in the CAS-FGOALS-f3 with high resolution are favorable for aerosol simulations. The HRM-simulated ARI (−2.35 W m−2) is generally lower than the LRM-simulated one (−3.40 W m−2) at top of the atmosphere, and the relative difference is about 30%, which is similar to the relative difference of AOD.