Observing the Diurnal Variation of Atmospheric Ozone From the Geostationary Interferometric Infrared Sounder (GIIRS) Over East Asia

Abstract Ozone is an important atmospheric constituent, exerting a pivotal influence on atmospheric chemistry, air quality, and climate change. The monitoring of its distribution and variation is crucial for advancing our understanding of ozone development and related processes. This study presents the first spatial and temporal distributions of total ozone columns (TOC) retrieved from the Geostationary Interferometric Infrared Sounder (GIIRS), on board China's FengYun‐4B satellite (FY‐4B/GIIRS) launched in 2021. Particularly, we focus on the variations of TOCs in East Asia from diurnal to seasonal time scales. Retrievals are implemented using spectra from March, June, September, and December, representing different seasons. The results show that the degree of freedom for the signal (DOFS) typically exhibited a range of 0.8–1.4, with the vertical detection sensitivity of GIIRS peaking in the upper troposphere/lower stratosphere (UTLS) region, where the ozone variability is the highest. Collocation comparisons with the Infrared Atmospheric Sounding Interferometer (IASI) retrievals, the Ozone Monitoring Instrument (OMI) measurements, the European Center for Medium‐Range Weather Forecasts (ECMWF) Reanalysis v5 (ERA5) simulations, and in situ ozone observations show good agreement. The comparisons of TOCs between GIIRS, Pandora and ERA5 at different latitudes and different time scales demonstrate the ability of FY‐4B/GIIRS in capturing the temporal and latitudinal ozone variations, particularly at middle and high latitudes. Our work demonstrates that FY‐4B/GIIRS has good capability to track ozone variations from diurnal to seasonal in East Asia, which will contribute to the understanding of regional and global ozone variations.