Function of ONU Spectrometer in South Korea

ONU spectrometers in South Korea are primarily used to monitor atmospheric trace gases such as NO2 and HCHO, providing high-precision measurements to support air quality assessment and satellite data validation.Ground-Based Monitoring with Pandora SpectrometersPandora spectrometer instruments (PSI) have been deployed at multiple sites across South Korea as part of the KORUS-AQ (Korea U.S.-Air Quality) campaign. These instruments perform direct-sun measurements to determine the total vertical column amounts of nitrogen dioxide (NO2) and formaldehyde (HCHO) in the atmosphere with high precision (0.05 DU) and accuracy (0.1 DU) using spectral fitting techniques. The data collected by these spectrometers are crucial for:Validating satellite observations such as those from the Ozone Monitoring Instrument (OMI) on NASA's AURA satellite. PSI measurements often show higher concentrations than satellite retrievals, highlighting the importance of ground-based validation for accurate air quality assessment.Assessing urban air pollution, particularly in densely populated areas like Seoul, where 30-day running averages of NO2 measured by PSI are at least twice as high as satellite averages.Supporting health impact studies, as accurate measurements of HCHO and NO2 help evaluate the effects of air pollution on human health. These spectrometers also allow comparisons with aircraft-based instruments, such as the Compact Atmospheric Multispecies Spectrometer (CAMS), to ensure comprehensive monitoring across different altitudes and locations.Satellite-Based Monitoring with GEMSThe Geostationary Environmental Monitoring Spectrometer (GEMS), launched on the GEO-KOMPSAT 2B satellite, complements ground-based spectrometers by providing continuous, geostationary observations of atmospheric trace gases over Asia. GEMS measures O3, NO2, SO2, HCHO, and other constituents in the troposphere and stratosphere with sub-nanometer spectral resolution, enabling:Diurnal monitoring of air pollutants, capturing variations throughout the day that low Earth orbit satellites cannot provide.Integration with ground-based data from instruments like PSI to improve the accuracy of air quality models and forecasts.Support for environmental policy and decision-making, as continuous monitoring helps track pollution trends and evaluate mitigation strategies.SummaryIn South Korea, ONU spectrometers, including Pandora ground-based instruments and GEMS satellite spectrometers, serve as essential tools for high-precision atmospheric monitoring. They provide critical data for validating satellite observations, assessing urban and regional air quality, and supporting research on the environmental and health impacts of pollutants such as NO2 and HCHO .