Further development and application of the WRFDA-Chem three-dimensional variational (3DVAR) system: Joint assimilation of satellite AOD retrievals and surface observations

The capability to assimilate Aerosol Optical Depth (AOD) is developed within the WRFDA system in this study using the three-dimensional variational (3DVar) algorithm, based on the Model for Simulating Aerosol Interactions and Chemistry (MOSAIC) aerosol scheme of the Weather Research and Forecasting model coupled with online Chemistry (WRF-Chem). Experiments assimilating Himawari-8 satellite AOD retrievals along with surface observations (PM 2.5, PM 10 , SO 2 , NO 2 , O 3 , and CO) are conducted over China for the period from 25 December 2016 to 9 January 2017.

The performances of data assimilation for both analyses and forecasts are evaluated against various datasets, including the surface PM 2.5 and PM 10 measurements, the Himawari-8 AOD and aerosol extinction coefficient (AEC) profile data from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). The DA experiments exhibit positive effects on the analyses and forecasts of surface PM 2.5 and PM 10 , AOD, and aerosol vertical extinction coefficient to different degrees.