<p>To understand the carbon cycle at policy-relevant spatial scales, a high density of high-quality CO<sub>2</sub> measurement sites is needed. In 2012, the Korea Meteorological Administration (KMA) installed CO<sub>2</sub> monitoring systems at Anmyeondo (AMY) in west, Jeju Gosan Suwolbong (JGS) in south-west and Ulleungdo (ULD) in east parts of Korea. Three stations were instrumented with identical greenhouse gas measurement systems based on Cavity Ring Down Spectroscopy (CRDS) and a new drying system developed by KMA and Korea Research Institute of Standards and Science (KRISS). This drying system is suitable in the humid areas; water vapour measured by the CRDS in ambient air was 0.001 to 0.004 % across the stations. Measurement uncertainties expressed by the quadrature sum of the uncertainties from the drying system, scale propagations, repeatability, and reproducibility were ~ 0.11 ppm from all KMA stations in 68 % confidence interval. Average monthly CO<sub>2</sub> enhancements above the local background at each station were 4.3 ± 3.3 ppm at AMY, 1.7 ± 1.3 ppm at JGS and  ± 1.9 ppm (1σ) at ULD respectively during 2012 to 2016. At AMY station, located between China and Korea, CO<sub>2</sub> annual means and seasonal variations are also greater than the other KMA stations indicating that it is affected not only by local vegetation, but also added anthropogenic sources. Selected baseline CO<sub>2</sub> at AMY and at JGS in the west part of Korea are more sensitive to East Asia according to wind direction and speed. Through the comparison of long-term trends and growth rates at AMY with other East Asian stations over 15 years, it was suggested that they could be affected by not only local vegetation but also measurement quality.</p>