Abstract
The Korea-United States Air Quality (KORUS-AQ) campaign is a joint study between the United States National Aeronautics and Space Administration (NASA) and the South Korea National Institute of Environmental Research (NIER) to monitor megacity and transboundary air pollution around the Korean Peninsula using airborne and ground-based measurements. Here, tropospheric nitrogen dioxide (NO2) slant column density (SCD) measurements were retrieved from Geostationary Trace and Aerosol Sensor Optimization (GeoTASO) L1B data during the KORUS-AQ campaign (May 1 to June 10, 2016). The retrieved SCDs were converted to tropospheric vertical column densities using the air mass factor (AMF) obtained from a radiative transfer calculation with trace gas profiles and aerosol property inputs simulated with the Community Multiscale Air Quality (CMAQ) model and surface reflectance data obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS). For the first time, we examine highly resolved (250 m × 250 m resolution) tropospheric NO2 over the Seoul and Busan metropolitan regions, and the industrial regions of Anmyeon. We reveal that the maximum NO2 VCDs were 4.94 × 1016 and 1.46 × 1017 molecules cm−2 at 9 AM and 3 PM over Seoul, respectively, 6.86 × 1016 and 4.89 × 1016 molecules cm−2 in the morning and afternoon over Busan, respectively, and 1.64 × 1016 molecules cm−2 over Anmyeon. The data retrieved from the GeoTASO airborne instrument were well correlated with those obtained from the Ozone Monitoring Instrument (OMI) (r = 0.65), NASA’s Pandora Spectrometer System (r = 0.84), and NO2 mixing ratios obtained from in situ measurements (r = 0.78 in the afternoon). Based on our results, GeoTASO is useful for identifying hotspots of NO2 and its spatial distribution in highly populated cities and industrial areas.
Highlights
Nitrogen dioxide (NO2) is one of the most important atmospheric trace gases and plays a key role in aerosol production and tropospheric ozone photochemistry (Boersma et al, 2004; Richter et al, 2005)
The NO2 concentration over major metropolitan cities in South Korea and China are over 3 times larger than over size cites in Europe and United States, despite NO2 concentration decreasing in China and South Korea
Geostationary Trace and Aerosol Sensor Optimization (GeoTASO) observed NO2 vertical column density (VCD) values three-times higher (>3 × 1016 molecules cm-2) in these areas compared to the surrounding rural areas
Summary
Nitrogen dioxide (NO2) is one of the most important atmospheric trace gases and plays a key role in aerosol production and tropospheric ozone photochemistry (Boersma et al, 2004; Richter et al, 2005). High NO2 concentrations in the Environmental Satellite Center, National Institute of Environmental Research, Hwangyeong-ro 42, Seo-gu, Incheon, Republic of Korea, 22689. Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland, USA 20740. The implementation of emission control technology and environmental regulation has led to a decrease in surface NO2 concentrations in Western Europe, the United States, and Japan in the last few decades (Richter et al, 2005). The NO2 concentration over major metropolitan cities in South Korea and China are over 3 times larger than over size cites in Europe and United States, despite NO2 concentration decreasing in China and South Korea (de Foy et al, 2016, Choo et al, 2020)
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