Retrieval of Hourly Three-dimensional Horizontal Winds using Combined GIIRS Radiance Observations from Fengyun-4A and Fengyun-4B

Continuous radiance measurements from geostationary hyperspectral infrared (IR) sounders can provide unprecedented four-dimensional information of atmospheric temperature and moisture with high temporal and vertical resolutions. By tracking the temporal changes of atmospheric moistures at different pressure levels, three-dimensional horizontal wind fields can be derived. Geosynchronous Interferometric Infrared Sounders (GIIRS) onboard Fengyun-4A was the first geostationary hyperspectral IR sounder, and the wind retrieval experiments have been conducted using its observations within targeted region with a high temporal resolution of 15 minutes. However, the temporal resolution of the operational observations is 2 hours, too long to accurately capture the changes of the atmospheric moisture features. With Fengyun-4B launched in 2021, it is possible to acquire atmospheric cube information at an hourly interval within the overlapped region using observations from dual-satellites. Considering the difference between FY-4A\GIIRS and FY-4B\GIIRS in spatial resolution, both the GIIRS measurements from Fengyun-4A and Fengyun-4B are matched to hourly gridded points of ERA5 to generate the weather cube, and three-dimensional horizontal winds are thus derived from continuous moisture information cube depicted by combined GIIRS radiance observations from both FY-4A and FY-4B using a convolutional neural network.