Global Climate Models Intercomparison of Anthropogenic Aerosols Effects on Regional Climate over North Pacific

Aerosols can alter cloud microphysics and macrophysics, which may further impact weather and global climate. With the development and industrialization of major Asian countries, anthropogenic aerosols have attracted considerable concerns and remain to be the largest uncertainty to estimates and interpretations of Earth's changing energy budget. Here we assess the performance of two stat-of-art global climate models (National Center for Atmospheric Research-Community Atmosphere Model 5 (CAM5) and Geophysical Fluid Dynamics Laboratory Atmosphere Model 3 (AM3)) by the impacts of anthropogenic aerosols on Pacific storm track region (30N – 50N, 120E -120W). Simulations are based on two aerosol scenarios, i.e. present day (PD) and pre-industrial (PI), to exhibit the long-range transport of anthropogenic aerosols across north Pacific. Both models show aerosol optical depth enhanced (AOD) by around 22%, with CAM5 AOD 40% lower in magnitude. Ice water path (IWP), stratiform precipitation, convergence and vertical velocity change in the two models show different trend and magnitude. AM3 generally shows qualitatively good agreement with long period satellite observations while CAM5 overestimates convection and liquid water path resulting in an underestimation of large-scale precipitation and IWP. Due to coarse resolution and parameterization in convection schemes, both models' performance on convection needs to be modified. Aerosols performance on large-scale circulation and radiative budget are also examined in this study.