Simulating aerosol-radiation effects on subseasonal prediction using the coupled Unified Forecast System and CCPP-Chem: prescribed aerosol climatology versus interactive aerosol model

• Main Authors: Sun, Shan, Grell, Georg A. A., Zhang, Li (Kate), Wang, Siyuan, Heinzeller, Dominikus, Li, Haiqin, Meixner, Jessica, Bhattacharjee, Partha Sarathi, Henderson, Judy
• Format: Other/Unknown Material
• Language: unknown
• Published: Authorea, Inc. 2024
• Subjects: Sea ice
• Online Access: http://dx.doi.org/10.22541/essoar.171352073.30888288/v1

This study investigates the effects of aerosol-radiation interaction on subseasonal prediction using the Unified Forecast System (UFS) with an ocean, a sea ice and a wave component, coupled to an aerosol component. The aerosol component is from the current NOAA operational GEFSv12-Aerosols model, which includes the GOCART aerosol modules simulating sulfate, dust, black carbon, organic carbon, and sea-salt. The modeled aerosol optical depth (AOD) is compared to reanalysis from Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA2) and observations from Moderate Resolution Imaging Spectro-radiometer (MODIS) satellite andAtmospheric Tomography (ATom) aircraft. Despite biases primarily in dust and sea salt, a good agreement in AOD is achieved globally. The simulated radiative forcing (RF) from the total aerosols at the top of the atmosphere is approximately -2.5 W/m2 or -16 W/m2 per unit AOD globally. This is consistent with previous studies. In subsequent simulations, prognostic aerosol component is substituted with climatological aerosol concentrations derived from initial experiments. While regional differences in RF are noticeable in specific events between these two experiments, the resulting RF, surface temperature, geopotential height at 500 hPa and precipitation, show similarities in multi-year subseasonal applications. This suggests that given the current capacities of the aerosol modeling, adopting a climatology of aerosol concentrations as a cost-effective substitute for the intricate aerosol module may be a practical approach for subseasonal applications.