Impacts of COVID-19 on NOx emissions and air quality in South Korea observed from satellites and in-situ monitors.

The COVID-19 broke out in the late 2019. The virus has spread uncontrollably across the world including South Korea. Accordingly, quarantine measures were taken in the affected areas, causing sharp drops in traffic and industrial activities. As nitrogen dioxide(NO₂) levels are highly influenced by anthropogenic emission changes, decreases in the NO₂ concentration were expected in South Korea and other regions. In this study, spaceborne NO₂ column observations with two high-resolution instruments, Tropospheric Monitoring Instrument(TROPOMI) on Sentinel-5 Precursor and Ozone Monitoring Instrument(OMI) on Aura are used to detect NO₂ concentration changes over the urban and remote areas in South Korea. Not only local restrictions on transport and decreases in industrial emissions in South Korea but also air pollution decreases in China may have impacts on air quality in South Korea. We will present the changes in the local and regional emissions and their impacts by analyzing both satellite and in-situ measurement.