Ground-based remote sensing of nitrous oxide (N2O) over Hefei, eastern China from high-resolution solar spectra

We for the first time demonstrate ground-based remote sensing of Nitrous Oxide (N 2 O) over Hefei in eastern China from high resolution Fourier Transform Infra-Red (FTIR) solar spectra. We have retrieved Column-averaged Abundance of N 2 O ( ${X_{{{\rm{N}}_2}{\rm{O}}}$ X N 2 O ) from both Near-Infrared (NIR, 4000 to 11,000 cm −1 ) and Mid-Infrared (MIR, 2400 to 3200 cm −1 ) solar spectra and inspected their agreement. Generally, NIR and MIR measurements agree well with a correlation coefficient of 0.86 and an average difference of (1.33 ± 4.05) ppbv (NIR - MIR). By correcting the bias of the two datasets, we combine the NIR and MIR measurements to investigate seasonality and inter-annual trend of ${X_{{{\rm{N}}_2}{\rm{O}}}$ X N 2 O over Hefei. The observed monthly mean time series of ${X_{{{\rm{N}}_2}{\rm{O}}}$ X N 2 O minimize in June and maximize in September, with values of (316.55 ± 12.22) ppbv and (322.05 ± 12.93) ppbv, respectively. The ${X_{{{\rm{N}}_2}{\rm{O}}}$ X N 2 O time series from 2015 to 2020 showed an inter-annual trend of (0.53 ± 0.10) %/year over Hefei, China. We also compared the FTIR ${X_{{{\rm{N}}_2}{\rm{O}}}$ X N 2 O observations with GEOS-Chem model ${X_{{{\rm{N}}_2}{\rm{O}}}$ X N 2 O simulations. They are in reasonable agreement with a correlation coefficient (R) of 0.71, but GEOS-Chem model underestimated the seasonality of the observations. This study can enhance current knowledge of ground-based high-resolution FTIR remote sensing of N 2 O in the atmosphere and contribute to generating a new reliable N 2 O dataset for climate change research.