Revision of 22-year Records of Atmospheric Baseline CO2 in South Korea: Application of the WMO X2019 CO2 Scale and a New Baseline Selection Method (NIMS Filter)

ABSTRACT

The Korea Meteorological Administration/National Institute of Meteorological Sciences (KMA/NIMS) has monitored atmospheric CO2 at Anmyeondo (AMY) World Meteorological Organization (WMO) Global Atmosphere Watch Programme (GAW) regional station since 1999, and expanded its observations at Jeju Gosan Suwolbong station (JGS) in the South and at Ulleungdo-Dokdo stations in the East (ULD and DOK) since 2012. Due to a recent WMO CO2 scale update and a new filter (NIMS) to select baseline levels at each station, the 22 years of CO2 data are recalculated. After correction for the new CO2 scale, we confirmed that those corrected records are reasonable within the compatibility goal (+/- 0.1 ppm of CO2) between KMA/NIMS and National Oceanic and Atmosphereic Administration (NOAA) flask-air measurements with the new scale. With the new NIMS filter, CO2 baseline levels are now more representative of the large-scale background compared to previous values, which contained large CO2 enhancements. Atmospheric CO2 observed in South Korea is 4 to 8 ppm greater than the global average while the amplitude of seasonal variation is similar (10 similar to 13 ppm) to the amplitude averaged over a comparable latitude zone (30 degrees N-60 degrees N). Variations in CO2 growth rate are also similar, increasing and decreasing similar to global values, as it reflects the net balance between terrestrial respiration and photosynthesis. In 2020, atmospheric CO2 continued increasing despite the COVID-19 pandemic. Even though fossil emission was reduced (around -7% globally), we still emitted large amounts of anthropogenic CO2. Overall, since CO2 has large natural variations and its source was derived from not only fossil fuel but also biomass burning, the small fossil emission reduction could not affect the atmospheric level directly.