Impact of Assimilation of FY-4A GIIRS Three-Dimensional Horizontal Wind Observations on Typhoon Forecasts

Measurements from a hyperspectral infrared (HIR) sounder onboard a satellite in geostationary orbit not only provide atmospheric thermodynamic information, but also can be used to infer dynamic information with high temporal resolution. Radiance measurements from the Geostationary Interferometric Infrared Sounder (GIIRS), obtained with 15-min temporal resolution during Typhoon Maria (2018) and 30-min temporal resolution during Typhoon Lekima (2019), were used to derive three-dimensional (3D) horizontal winds by tracking the motion of atmospheric moisture. This work focused on the impact of assimilation of 3D winds on typhoon analyses and forecasts using the operational NWP model of the China Meteorological Administration (CMA-MESO), and improved understanding of the potential benefits of assimilating dynamic information from geostationary sounder data with higher temporal resolution. The standard deviation of the observations minus simulations revealed that the accuracy of the derived 3D winds with 15-min resolution was higher than that of derived winds with 30-min resolution. Experiments showed that the assimilation system can effectively absorb the information of the derived 3D winds, and that dynamic information from clear-sky areas can be transferred to typhoon areas. In typhoon prediction, assimilation of the derived 3D winds had greatest influence on the typhoon track, and less influence on the maximum wind speed. Assimilation of the derived 3D winds reduced the average track error by 17.4% for Typhoon Maria (2018) and by 3.5% for Typhoon Lekima (2019) during their entire 36-h forecasts initiated at different times. Assimilation of GIIRS dynamic information can substantially improve forecasts of heavy precipitation by CMA-MESO. Results indicate that the assimilation of dynamic information from high-temporal-resolution geostationary HIR sounder data adds value for improved numerical weather prediction. (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(HIR)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)Maria(2018)15(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)Lekima(2019)30(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(GIIRS)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(3D)(sic)(sic). (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(CMA-MESO), (sic)(sic)(sic)(sic)3D(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), 15(sic)(sic)(sic)(sic)(sic)(sic)3D(sic)(sic)(sic)(sic)(sic)(sic)30(sic)(sic)(sic)(sic)(sic)(sic)3D(sic)(sic). (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)3D(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic), 3D(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). 3D(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)Maria(2018)(sic)(sic)(sic)36(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)17.4%, (sic)(sic)(sic)Lekima(2019)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)3.5%, (sic)(sic)(sic)(sic)(sic)CMA-MESO(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).