Using Multisensor Aerosol Optical Depth Retrievals to Improve Infrared Radiance Assimilation

This study investigates the impact of assimilating of aerosol-affected radiances into the Goddard Earth Observing System Model, version 5 (GEOS-5) within the Gridpoint Statistical Interpolation (GSI) system. Previous research has conclusive evidence that coarse mode dust particles possess strong scattering and absorbing properties at infrared wavelengths, which affirms the importance of accounting for these particles when simulating infrared radiances. However, their impact on simulated infrared radiances is currently ignored, which can lead to the assimilation of unrepresentative radiances into numerical models and subsequent errors in the model analysis and forecast. In this study, we first validate the Community Radiative Transfer Model (CRTM) aerosol module by simulating dust-aerosol affected radiances for intensive case studies where aerosol vertical profiles from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) were available, which served as input into the CRTM. Simulated infrared radiances and brightness temperatures from the CRTM are compared to those observed from the Advanced Himawari-8 Imager (AHI) and Moderate Resolution Imaging Spectroradiometer (MODIS) for Asian and Saharan dust events, and our initial results highlight a need for further refinements in the CRTM aerosol module. We also present results from experimental simulations incorporating aerosol information from polar-orbiting and geostationary sensors into the CRTM to show the impact of geostationary data on simulated aerosol-affected infrared radiances. Finally, we conduct 24-h forecasts using the GEOS-5/GSI framework for assimilating aerosol-infrared radiances for Asian and Saharan dust events. The overall impact on model analysis and forecast fields are thoroughly evaluated in this study.