Observation of greenhouse gas vertical profiles in the boundary layer of the Mount Qomolangma region using a multirotor UAV

Abstract. Understanding the vertical profile of greenhouse gases (GHGs) is crucial for elucidating their sources and sinks, transport pathways, and influence on Earth's radiative balance, as well as for enhancing predictive capabilities for climate change. Remote sensing methods for measuring vertical GHG profiles often involve substantial uncertainties, while in situ measurements are limited by high equipment costs and operational expenses, rendering them impractical for long-term continuous observation efforts. In this study, we have developed an automatic low-cost and user-friendly multi-altitude atmospheric sampling device designed for small- and medium-sized unoccupied aerial vehicles (UAVs), balloons, and other flight platforms. A field campaign was carried out in the Mount Qomolangma (also known as Mount Everest) region, at an average surface altitude of 4300 m above sea level (a.s.l.). During the campaign, we conducted 15 flights and collected 139 samples from the ground surface up to a height of 1215 m using a hexacopter UAV platform equipped with the sampling device. The samples were analyzed using the Agilent gas chromatography (GC) 7890A instrument, enabling the derivation of the vertical profiles for four GHG species (CO2, CH4, N2O, and SF6) within the boundary layer of the Mount Qomolangma region. To enable long-term monitoring using small UAVs, future efforts should prioritize reducing the weight of the equipment and improving the sampling efficiency.