Assimilation of METOP-B/IASI Water Vapor Channel Data in CMA-GFS and Its Impact on Forecasting

This study assimilated data from 9 Water Vapor(WV) channels of Metop-B IASI into the CMA-GFS 4DVAR system. Two sets of experiments, METOP-B-IR and CTRL, were designed, conducting an 18-day cycle assimilation test to evaluate the impact of assimilating MetOp-B IASI water vapor data on CMA-GFS model’s analysis and forecasting fields. By using ECMWF reanalysis data ERA5 as a reference, the study demonstrated that after assimilating 9 WV data, there was certain extent of improvement in the humidity and wind fields and led to slightly positive improvements in the forecasting skills.