Emission characteristics of greenhouse gases and air pollutants in a Qinghai-Tibetan Plateau city using a portable Fourier transform spectrometer and TROPOMI observations

Abstract. Despite the critical need to understand greenhouse gas and air pollutant concentrations and their emissions characteristics in urban and industrial areas, limited assessments have been conducted in the Qinghai-Tibetan Plateau (QTP) cities. Herein, for the first time, we present CO2, CH4 and CO column abundances using a portal Fourier-transform infrared spectrometer (EM27/SUN) in Ganhe Industrial Park (36.546° N, 101.518° E, 2603 m a.s.l.), located in the suburbs of Xining, Qinghai Province, during May–June 2024. Ground-based measurements found to be higher than spaceborne measurements (TROPOMI and IASI) and model forecast (CAMS) across all investigated species, indicating higher local emissions. Notably, significant discrepancies in CO levels are observed, particularly under easterly wind conditions, which transport polluted airmasses from Xining city. To further quantify emissions, we applied a simple dispersion model to the EM27/SUN data and TROPOMI products, estimating an average CO emission rate of 12.3 ± 9.6 and 8.9 ± 7.5 kg s−1, respectively. A wind-assigned anomaly method further applied to the TROPOMI dataset yielded a CO emission rate of 8.5 kg s−1. Additionally, the ground-based observations of ΔXCO / ΔXCO2 ratio exhibits a strong correlation under easterly winds, which suggests an average CO2 emission rate of 550 kg s−1 from Xining city. These findings underscore the utility of portable FTIR spectrometers to enhance our understanding of urban emissions at QTP and demonstrate the potential of combining collaborative ground-based and spaced-based observations to estimate CO2 emissions, particularly in regions with sparse CO2 measurement coverage.