Spatial and temporal variations of CO<sub>2</sub> mole fractions observed at Beijing, Xianghe, and Xinglong in North China

Abstract. Atmospheric CO2 mole fractions are observed at Beijing (BJ), Xianghe (XH), and Xinglong (XL) in North China using Picarro G2301 cavity ring-down spectroscopy instruments. The measurement system is described comprehensively for the first time. geographical distances among these three sites within 200 km, but they have very different surrounding environments: BJ inside megacity; XH suburban area; XL countryside on a mountain. mean standard deviation of BJ, XH, between October 2018 September 2019 448.4±12.8, 436.0±9.2, 420.6±8.2 ppm, respectively. seasonal variations similar, with maximum winter minimum summer, which dominated by terrestrial ecosystem. However, more affected human activities as compared to XL. Using background, enhancements simultaneously XH. diurnal driven boundary layer height, photosynthesis, We also compare measurements five urban USA, it found that concentration largest. Moreover, we address impact wind This study provides an insight into spatial temporal China.