Comparison of Atmospheric CO₂, CH₄, and CO at Two Stations in the Tibetan Plateau of China

Abstract

The research of greenhouse gases on the Tibetan Plateau is of great importance since its unique topography as the third pole of our planet and profound response on the climate change. In this study, we compared the concurrent observations of atmospheric carbon dioxide (CO 2 ), methane (CH 4 ), and carbon monoxide (CO) during 2010-2016 from two stations located on the Tibetan Plateau, which are Mt. Waliguan station (WLG), the only World Meteorological Organization/Global Atmosphere Watch global station in the inland of Eurasia, and Shangri-La station, a Chinese national station (XGLL). Although both stations are located at remote area, the atmospheric CO 2 , CH 4 , and CO concentrations are frequently influenced by regional sources, especially for XGLL throughout the year and WLG in summer. Due to the unique topography and regional conditions, the atmospheric CH 4 and CO at both stations display different trends with other sites in China, with higher values in summer. The atmospheric CO 2 , CH 4 , and CO at the XGLL mainly represent the conditions in regional scale. As the only World Meteorological Organization/Global Atmosphere Watch global station in the inland of Eurasia, the observation results at WLG can be used to represent the conditions on the Tibetan Plateau, but some of them are frequently influenced by the emissions from the cities located on the east or north east, and some even can be affect by emissions from the Ganges basin in autumn and winter, which should be treated with caution. By subtracting the influences of the cities, we updated the growth rate of 2.45 ± 0.02 ppm yr −1 for CO 2 , 8.2 ± 0.1 ppb yr −1 for CH 4 , and −0.4 ± 0.1 ppb yr −1 for CO, compared to the prior estimation of 2.31 ± 0.02 ppm yr −1 for CO 2 , 8.1 ± 0.1 ppb yr −1 for CH 4 , and −0.6 ± 0.1 ppb yr −1 for CO on the Tibetan Plateau.

Potential Source Regions and Transportation Pathways of Reactive Gases at a Regional Background Site in Northwestern China

“…e highest hourly average of Akedala's CO concentration was below 700 ppb and was at its highest level during the winter, with an average of 123.78 ± 73.35 ppb and a median of 102.75 ppb. Compared to other local stations, it was lower than the CO concentration level of the Lin'an (372.5 ± 0.6 ppb) [55] and Shangdianzi background stations (159.4 ± 0.4 ppb) [53] and was similar to Shangri-La and Wariguan in western China [56]. e main reason for this could be that the atmospheric CO at the eastern stations is primarily affected by the air masses emitted by nearby megacities and the monsoons, reflecting the impacts of man-made pollution.…”

“…Specifically, for the Chinese background stations, the combination of airflow trajectory statistics, PSCF, and CWT reveals that the air trajectory of Shangdianzi GAW station shows a southeastern trend in summer and is mainly affected by the northwestern path in other seasons, which are mainly reflected in the background information of Beijing, Hebei, Tianjin, and Inner Mongolia [104]. Moreover, the Mt Waliguan GAW station mainly reflected the pollution sources of Qinghai, Tibet, and Gansu [56,57]. e results of WPSCF show that the overseas potential source areas of CO 2 and CO in Shangri-La are mainly located in South Asia, such as Myanmar, Bangladesh, and northern India [105].…”

Changes of Atmospheric CO2 in the Tibetan Plateau From 1994 to 2019

“…The decreased CO 2 mole fraction in the daytime could be attributed to photosynthesis uptake, especially in the summer season. After sunset, due to weak vegetation uptake, increased respiration, and lower boundary layer height, the CO 2 mole fraction reaches a stable period and begins to gradually accumulate (Guo et al., 2020; Zhang, Zhou, & Xu, 2013; Zhang, Zhou, Conway, et al., 2013). Temperature and solar radiation are also the main drivers because their increase or decrease affects the intensity of photosynthesis and soil respiration throughout a day, thus affecting CO 2 accumulation (Fang et al., 2014; Jing et al., 2010; Patil et al., 2014).…”

Evolution of Atmospheric Carbon Dioxide and Methane Mole Fractions in the Yangtze River Delta, China

“…Nguyen et al [67] presented 20-year (2001-2020) records of atmospheric CO 2 at Lutjewad in the Netherlands and Mace Head in Ireland, with annual growth rates of 2.31 ± 0.07 ppm yr −1 and 2.22 ± 0.04 ppm yr −1 , respectively. The higher growth rate indicated that there was a strong difference between economically developed zones and remote areas, and the LAN station was strongly influenced by regional sources/sinks [59,68]. In addition, the annual average growth rate of CO 2 at LAN was lower than that at LFS and SDZ because LFS and SDZ were located in Northeast and North China, respectively, where fossil fuel consumption was high in heavy industry and winter heating [21,58].…”