EGUsphere EGUsphere EGUsphere EGUsphere Copernicus Publications Göttingen, Germany 10.5194/egusphere-2025-1293 Greenhouse gas measurement campaign of the Earth Summit Mission-2022: ground-based in situ and FTIR observations and contribute to satellite validation in the Qomolangma region Zhou Minqiang https://orcid.org/0000-0003-3427-5873 1 3 Wang Yilong https://orcid.org/0000-0001-7176-2692 2 3 Duan Minzheng 3 4 Tian Xiangjun 2 3 Ding Jinzhi 2 3 Bi Jianrong 5 Ma Yaoming https://orcid.org/0000-0001-8387-8721 2 6 Ma Weiqiang https://orcid.org/0000-0003-4334-8042 2 6 Xi Zhenhua 2 6 State Key Laboratory of Atmospheric Environment end Extreme Meteorology, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China State Key Laboratory of Tibetan Plateau Earth System, Environment and Resources, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China University of Chinese Academy of Sciences, Beijing 100049, China Key Laboratory for Middle Atmosphere and Global Environment Observation, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou, China National Observation and Research Station for Qomolongma Special Atmospheric Processes and Environmental Changes, Dingri 858200, China 28 03 2025 2025 1 22 Copyright: © 2025 Minqiang Zhou et al. 2025 This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ This article is available from https://egusphere.copernicus.org/preprints/2025/egusphere-2025-1293/ The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2025/egusphere-2025-1293/egusphere-2025-1293.pdf

The Qinghai-Tibetan Plateau (QTP) is a key system that impacts the global carbon balance, but greenhouse gases (GHGs) mole fraction measurements in this region are limited due to the tough environment. Supported by the Second Tibetan Plateau Scientific Expedition Program, we carried out an integrated GHG measurement campaign in May 2022 as part of the Earth Summit Mission-2022 at the Qomolangma station for atmospheric and environmental observation and research (QOMS; 28.362&deg; N, 86.949&deg; E, 4276 m a.s.l.). In this study, the first GHG column-averaged mole fraction measurements (Xgas) at QOMS are presented, including XCO<sub>2</sub>, XCH<sub>4</sub>, XCO, and XN<sub>2</sub>O, derived from a ground-based Fourier-transform infrared spectrometer (FTIR; Bruker EM27/SUN). We then compare them to surface <em>in situ</em> and satellite (TROPOMI and OCO-2) measurements. The mean FTIR XCO<sub>2</sub> and XCH<sub>4</sub> are 7.8 ppm and 97 ppb less than those near the surface, respectively. The difference between OCO-2 land nadir and EM27/SUN XCO<sub>2</sub> measurements is 0.21&plusmn;0.98 ppm, which is consistent with OCO-2 retrieval uncertainty. However, a relatively large bias (1.21&plusmn;1.29 ppm) is found for OCO-2 glint XCO<sub>2</sub> measurements, which is related to the surface albedos and surface altitudes. The EM27/SUN measurements indicate that the uncertainty of OCO-2 satellite XCO<sub>2</sub> measurements is relatively large in the QTP mountain region and its quality needs to be further assessed. The difference between FTIR and TROPOMI XCO measurements is -5.06&plusmn;5.36 (1s) ppb (-4.7&plusmn;5.1%) within the satellite retrieval uncertainty. The XCO measurements at QOMS show the local airmass is largely influenced by atmospheric transport from southern Asia, and it is important to carry out long-term measurements to quantify the contribution of the cross-regional transport in this region.