Research on the Assimilation Application of FY-3E/HIRAS-II Infrared Hyperspectral Data in Global Atmospheric Real-time Analysis System.

This study investigates the direct assimilation of Level-1 data from the FY-3E Hyperspectral Infrared Atmospheric Sounder (HIRAS-II) within the Global Atmospheric Real-time Analysis System. A complete operational processing chain for HIRAS-II data was developed based on the GSI assimilation framework, encompassing data preprocessing, quality control, bias correction, cloud detection, and variational assimilation. By integrating the CrIS-FSR channel selection approach with Jacobian sensitivity analysis from HIRAS-II, a subset of 28 channels within the long-wave band with high sensitivity to temperature was optimally selected. Assimilation experiments demonstrate that the final channel subset significantly enhances the assimilation performance of the temperature field while effectively suppressing humidity-related errors. It reduces analysis errors in mid- and upper-level temperatures, maintains a positive impact in the lower levels, and achieves a maximum RMSE reduction of 2% in the Northern Hemisphere temperature field. This study demonstrates the effective assimilation of FY-3E/HIRAS-II data in the global atmospheric real-time analysis system and provides reliable technical support for the operational application of Fengyun satellite hyperspectral infrared data.