Retrieval of SO2 columns from FY-3F/OMS instrument observations

Atmospheric SO2 plays an important role in air quality and climate. Satellite remote sensing enables continuous monitoring of SO2 from volcanic and anthropogenic sources. The Ozone Monitoring Suite (OMS) onboard the Chinese FY-3F satellite, launched in August 2023, is a new hyperspectral UV–VIS instrument designed for atmospheric trace gas observations. Here we present the global retrieval of SO2 columns from FY-3F/OMS nadir measurements using a Differential Optical Absorption Spectroscopy (DOAS) approach. Instrument-specific processing schemes, including solar spectrum selection, spectral soft calibration, and background offset correction, were developed to mitigate along-track striping and across-track asymmetry in the initial retrievals. The FY-3F/OMS SO2 products are evaluated against TROPOMI SO2 retrievals over clean oceanic regions, volcanic plumes, and anthropogenic emission areas. The results demonstrate good stability over clean regions (precision ~0.15 DU) and a clear capability to detect both volcanic and anthropogenic SO2 enhancements. Remaining uncertainties are mainly related to detector non-uniformity and AMF. These results provide a first assessment of the FY-3F/OMS capability for global SO2 monitoring.