Aerosol Optical Properties in the Community Radiative Transfer Model for Data Assimilation

Aerosol particles have significant impacts across the Earth System, yet quantifying these impacts remains challenging. An effective technique to predict aerosol distribution and study their impact is data assimilation (DA), for which the aerosol optical properties (AOPs) are critical. AOPs govern the interaction of light with aerosols, serve as the fundamental parameters in aerosol retrieval algorithms, and link the modeled aerosol concentration to retrieval products, such as aerosol optical depth (AOD). Ensuring consistent and scientifically accurate AOPs across aerosol models, observation, and observation operators is therefore essential for aerosol DA. To support this need, on top of the default aerosol scheme developed and adopted by NOAA, the Community Radiative Transfer Model (CRTM) team has implemented and released three optional aerosol schemes in recent years to facilitate aerosol DA with the Community Multiscale Air Quality, NAAPS, and GOCART‐GEOS5 models. In this paper, we present updates to the CRTM aerosol component, examine the impacts of different aerosol schemes on simulated AOD and brightness temperature, and compare the AOPs used in the selected chemical transport model and satellite retrieval algorithms, including Dark Target and Deep Blue. This work aims to better constrain AOPs across selected DA systems and discusses the recent progress as well as remaining challenges.