Improvement of the Aerosol Forecast and Analysis Over East Asia With Joint Assimilation of Two Geostationary Satellite Observations.

Here we present the first simultaneous assimilation of aerosol optical thicknesses (AOTs) over East Asia retrieved from two next‐generation geostationary satellites named Fengyun‐4A (FY‐4A) and Himawari‐8 with an advanced data assimilation system. A new stringent data‐control method is proposed to assimilate only the high quality aerosol products of FY‐4A. The AOTs retrieved from the two geostationary satellites are both comparable to the ground‐based observations over East Asia, and the FY‐4A provides twice the number of the Himawari‐8 AOT retrievals. Validations with independent observations demonstrate the joint assimilation significantly improve the aerosol analysis and forecast skill over East Asia especially in South China, reducing the model biases of 70% and 40%. The aerosol model performances at 95% independent 61 ground‐based sites are more benefited from joint assimilation than single‐sensor assimilation. This demonstrates the high impact and innovative application of joint assimilation technique in the air quality modeling. Plain Language Summary: Fengyun‐4A (FY‐4A) and Himawari‐8, China's and Japan's next‐generation geostationary satellites, can both provide the aerosol monitoring with high temporal‐spatial resolution. However, the coverage areas and sampling numbers from only one geostationary satellite are still insufficient to dramatically advance the aerosol performance. In this study, we present the first application of aerosol optical thicknesses retrieved from FY‐4A and Himawari‐8 to reveal the benefits of joint assimilation on the aerosol forecast and analysis performances over East Asia. Key Points: A new quality‐control method making the best quality of Fengyun‐4A aerosol products for data assimilation is proposedIt is the first attempt to simultaneously assimilate aerosol optical thicknesses (AOTs) from two geostationary satellites with an advanced data assimilation systemJointly assimilating AOTs of two geostationary satellites significantly enhances model performances over East Asia [ABSTRACT FROM AUTHOR]

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