Identifying needs for urban greenhouse gas monitoring in Seoul using ground-based EM27/SUN measurements

Anthropogenic emissions of greenhouse gases from fossil fuel combustion have a significant impact on the global climate. Cities, which are home to more than half of the global population, account for over 70% of anthropogenic greenhouse gas emissions and are the major sources of air pollution that we face today. However, as much as they are big emitters, cities also have great potential to be drivers of global greenhouse gas reductions. To better manage atmospheric greenhouse gases, it is necessary to accurately monitor and quantify emissions at all spatial scales from national to urban levels. In addition to using satellites which provide global coverage with high space and time resolutions for greenhouse gas monitoring, several studies have used portable ground-based remote sensing Fourier transform infrared (FTIR) spectrometers, EM27/SUNs, to measure the column-averaged concentrations of greenhouse gases. This study analyzes the column-averaged dry air mole fractions of CO₂, CH₄, and CO (XCO₂, XCH₄, XCO) in the atmosphere over Seoul using two EM27/SUNs which is the first to be done in South Korea. Moreover, we compare our measurements with satellite measurements of the Orbiting Carbon Observatory-2 (OCO-2), Orbiting Carbon Observatory-3 (OCO-3), and Sentinel-5 Precursor TROPOspheric Monitoring Instrument (TROPOMI). Together, this study aims to analyze the three-dimensional structure of greenhouse gases in Seoul which has been difficult to do due to the absence of domestic greenhouse gas observation satellites. Furthermore, this study identifies the need for more ground-based column measurements of greenhouse gases in cities and plume areas, as well as locally adaptable methods of greenhouse gas emissions monitoring in urban areas.