Development of Capabilities to Assimilate ABI GOES ‐18 Satellite Radiance in NGFS Modeling System and Its Application in Simulation of Pacific Hurricane Hilary

The Advanced Baseline Imager (ABI) onboard the geostationary satellite GOES‐18, launched on March 14, 2022, and re‐designated as GOES‐West in January 2023, has been providing data to the National Centre for Medium Range Weather Forecasting (NCMRWF) since its operational commencement. This study endeavors to develop and evaluate GOES‐18 satellite radiance data assimilation within the Global Data Assimilation System (GDAS) at NCMRWF, specifically on simulating Pacific hurricanes impacting the Western United States. The study includes two main components: (1) developing and assessing the reliability of the GOES‐18 radiance observation assimilation capability in the NCMRWF Global Forecasting System (NGFS), and (2) simulating and analyzing the catastrophic Category‐4 hurricane Hilary, which caused severe damage and heavy rain in the Western United States and Mexico. A month‐long analysis of data reveals that GOES‐18 provides a substantially larger number of observations compared to GOES‐16, with a more significant proportion of observations being accepted during the assimilation cycle. Error metrics (e.g., spread, standard deviation, RMSE) were estimated for background fields without bias correction, with BC, and analysis with BC compared to observations. The results indicate a significant reduction in RMSE (~50%) in the analysis, thereby establishing a positive signature for the assimilation of GOES‐18 observations. This study further investigates the efficacy of assimilating GOES‐18 data in simulating hurricane Hilary using the NGFS with a focus on evaluating potential improvements in track, intensity, and inner core structure of the system.