Evaluating Direct Effect of Aerosol on Subseasonal Prediction using a Coupled UFS with the GEFS Aerosol Model

The direct effect of aerosols on subseasonal prediction is investigated using the global coupled Unified Forecast System (UFS) with atmosphere, aerosol, ocean, ice and wave components. Twin experiments are carried out using MERRA-2 climatological aerosols as well as an aerosol component from the GEFS-Aerosols model based on GOCART. Anthropogenic emissions are obtained from CEDS-2014, and fire emissions from the GFAS real-time data. The 32-day long experiments with aerosol initial conditions are performed for May and September respectively from 2003 to 2019. Model simulated aerosol optical depth from the GEFS-Aerosols model is closer to satellite observations than that from the MERRA-2 climatological aerosols. The effects of interactive aerosols on surface radiation, cloudiness and precipitation, both locally and globally, are examined in different seasons between the experiments using MERRA-2 climatological aerosols and online simulated aerosols using the aerosol model.