Preliminary GEMS L2 validation results using ground-based measurements during the ASIA-AQ/SIJAQ campaign

To validate L2 data of the Geostationary Environment Monitoring Spectrometer (GEMS) and to understand the causes of particulate matter generation in winter season, the National Institute of Environmental Research (NIER) in Korea and the National Aeronautics and Space Administration (NASA) in the U.S. will carry out a field campaign over four Asian countries (South Korea, the Philippines, Malaysia, and Thailand) in February through March 2024. In this campaign, NIER will install 12 ground-based remote sensing instruments such as Pandora, Max-DOAS, and AQ-Profiler in and around the Seoul metropolitan area and  retrieve nitrogen dioxide (NO2), formaldehyde, ozone vertical column density, NO2 vertical profile as well as aerosol properties (aerosol optical depth, single scattering albedo, size distribution, etc.). Especially, to investigate pixel inhomogeneity, we installed four instruments around an industrial complex within one GEMS pixel. During this campaign, NASA will observe NO2 and HCHO vertical column density using air-borne remote sensing instruments (e.g., GCAS: GeoCAPE airborne Simulator). Through this campaign, we plan to validate the performance of GEMS L2 data using ground-based and airborne measurements.