Performance Evaluation of a Grating-Based Hyperspectral System for CH4 Remote Sensing

Abstract

Accurate measurements of atmospheric methane (CH4) columns are essential for emission monitoring and satellite validation. In this study, a grating-based hyperspectral atmospheric greenhouse gas remote sensing system hyperspectral atmospheric greenhouse gas remote sensor (HAGRES), previously demonstrated for atmospheric CO2 observations, is extended to atmospheric CH4 remote sensing for the first time using high-resolution direct solar absorption spectra within the 1627.3–1677.8 nm spectral window. Retrieval uncertainties are evaluated through sensitivity analyses considering major error sources. System performance is assessed against observations from the Hefei site of the Total Carbon Column Observing Network (TCCON), the recognized reference standard for ground-based greenhouse gas column measurements, using seven months of coincident observations (December 2024–June 2025). HAGRES shows excellent agreement with TCCON, with a mean relative bias of (−0.16% $\pm ~0.27$ %) and a correlation coefficient of 0.98. Comparisons with EM27/SUN and Greenhouse Gases Observing Satellite (GOSAT) observations further demonstrate the reliability and consistency of the proposed system. These results demonstrate that the grating-based HAGRES system can provide stable and high-precision atmospheric CH4 column observations during extended outdoor operation, highlighting its potential for long-term greenhouse gas monitoring.