Retrieval of High-Resolution Tropospheric NO₂ VCDs from Airborne EMSA Observations over the Industrial Areas in Yeosu, Korea

Accurate quantification of tropospheric nitrogen dioxide (NO₂) at high spatial resolution is crucial for monitoring air pollution emissions and validating the environmental satellites, including the GEMS (Geostationary Environment Monitoring Spectrometer). In this study, we present the retrieval and analysis of high-resolution NO₂ Vertical Column Densities (VCDs) using airborne hyperspectral observations from the EMSA (Environmental Monitoring Spectrometer for Aircraft) over Yeosu’s industrial complexes in Korea

To ensure retrieval accuracy, Level 1B spectra were first generated through precise radiometric calibration, spectral calibration, and geometric (INR) correction. The NO₂ Slant Column Densities (SCDs) were retrieved using the QDOAS algorithm with an optimized spectral fitting window (420–460 nm) selected to minimize interference. These SCDs were subsequently converted to Vertical Column Densities (VCDs) using Air Mass Factors (AMFs) calculated by the VLIDORT radiative transfer model, incorporating aerosol properties and surface albedo data.

Finally, the airborne NO₂ VCDs were compared with coincident GEMS measurements. The preliminary analysis reveals a consistent spatial distribution between the high-resolution airborne data and satellite observations, particularly in capturing point-source emissions. This study demonstrates that EMSA observations effectively resolve local emission sources unresolved by satellites, serving as a valuable reference dataset for validating GEMS Level 2 products. Detailed validation statistics, including correlation analysis with GEMS, will be presented.