Aerosol effective height retrieval using O4 absorption property based on GEMS measurements

In this study, we developed an aerosol effective height (AEH) retrieval algorithm based on O₄ absorption properties at 477 nm from the hyperspectral measurements of the Geostationary Environment Monitoring Spectrometer (GEMS). The GEMS, successfully launched in February 2020 onboard Geostationary Korea Multi-Purpose SATellite (GeoKOMPSAT-2B), is currently monitoring the air quality (O₃, NO₂, SO₂, HCHO, and aerosol) over Asia. In the AEH retrieval algorithm, an O₄ slant column density (SCD) is retrieved using the differential optical absorption spectroscopy (DOAS) technique, then the O₄ air mass factor (AMF) is derived by dividing O₄ SCD by O₄ vertical column density (VCD) to account for the variation of O₄ VCD associated with changes in atmospheric temperature and pressure. A spatiotemporal variation of O₄ VCD and its effect on AEH retrieval accuracy was investigated. In addition, a temperature-dependent cross-section for O₄ (TDCS) was applied to the O₄ AMF calculation. The AEHs were retrieved from hyperspectral radiance from the GEMS measurements for the Asian dust period in 2021. Additionally, we tried to compare the retrieved GEMS AEH with lidar measurement data to validate the performance of our retrieval.