Atmospheric propane (C₃H₈) column retrievals from ground-based FTIR observations in Xianghe, China

Abstract

Propane (C3H8) is an important trace gas in the atmosphere, as it is a proxy for oil and gas production and has a significant impact on atmospheric chemical reactions related to the hydroxyl radical and tropospheric ozone formation. In this study, solar direct absorption spectra near 2967 cm−1 recorded by a ground-based Fourier transform infrared spectrometer (FTIR) were applied to retrieve C3H8 total columns between June 2018 and July 2022 in Xianghe in north China. The systematic and random uncertainties of the C3H8 column retrieval are estimated to be 18.4 % and 18.1 %, respectively. The mean and standard deviation of the C3H8 columns derived from the FTIR spectra in Xianghe are 1.80 ± 0.81 (1σ) × 1015 molec. cm−2. Good correlations are found between C3H8 and other non-methane hydrocarbons, such as C2H6 (R=0.84) and C2H2 (R=0.79), as well as between C3H8 and CO (R=0.72). However, the correlation between C3H8 and CH4 is relatively weak (R=0.45). Moreover, the FTIR C3H8 measurements in Xianghe are also compared against MkIV measurements at several sites around the world. The new FTIR measurements in Xianghe provide us with insight into C3H8 column variations and the underlying processes in north China.