Variations of atmospheric CO concentration from 2004 to 2019 at the Mt. Waliguan station in China

Abstract

Carbon monoxide (CO) is an important indirect greenhouse gas and has been measuring by many sites around the world. In this study, a 14-years (2004–2007 as well as 2010–2019) observed atmospheric CO record at the Mount. Waliguan (WLG), the only global station of the World Meteorological Organization (WMO) and Global Atmosphere Watch (GAW) in Eurasia, was presented. The characteristics of atmospheric CO including daily and seasonal cycles, long-term trends, and spatiotemporal source distributions in different episode were compared and analyzed. Our results show that there was an increasing trend for atmospheric CO with the highest annual average of 129.7 ± 0.2 (σ = 4.6) ppb in 2007 in earlier years but a decreasing trend in later years with an annual average of 110.7 ± 0.2 (σ = 5.3) ppb in 2019. The characteristics of atmospheric CO at the site was dominated by regional economy development strategy such as the China's western development strategy, carbon emission reduction strategy in China's economic development plan. After the infrastructure construction period from 2004 to 2007, the regional emissions of CO at the Qinghai and Gansu provinces stimulated the atmospheric CO at the WLG and changed the patterns of seasonal variation, source regions as well as the long-term trends. A weak decreasing trend with value of −0.47 (σ = 0.01) ppb yr−1 was observed during the observation period, which was less than most of the stations in China. On the whole, we concluded that the CO mole fractions observed at the Mt. Waliguan station might only denote the conditions in regional scale instead of the well mixed condition in Eurasia.