Current Status of Point Source Spaceborne Methane Satellite Development

Methane emission inventories typically employ a bottom-up approach, linking emissions to related production activities to inform emission control strategies. Top-down atmospheric methane observations, on the other hand, use a reverse approach to improve methane emission concentration estimation. Satellite-based methane observations have attracted significant attention due to their high observation frequency and global coverage. Among these, atmospheric methane column concentration detection using shortwave infrared spectroscopy can achieve near-unit-level detection sensitivity.

△ Shortwave Infrared (SWIR) Methane Satellite Instrument

Depending on the observation objective, shortwave infrared methane satellite payloads can be divided into two main categories: regional and point source. Regional imagers aim to observe total emissions at a global or regional scale with a spatial resolution of 0.1–10 km. Point source imagers offer high spatial resolution (

△Classification of atmospheric methane detection at global, regional, and point source scales

The potential of spaceborne land imaging spectrometers to detect methane point sources was first demonstrated during the detection of a natural gas leak at the Ariso Canyon gas storage facility using the Hyperion spectrometer. Hyperspectral sensors such as PRISMA have been shown to quantify methane point source emissions of approximately 500 kg h⁻¹. The GHGSat-D satellite, launched in 2016 as the first dedicated satellite for methane point source quantification, has an effective pixel resolution of 50 × 50 m² and an accuracy of 12%–25% (depending on surface type). Between 2020 and 2022, five more GHGSat series satellites with an accuracy of approximately 1%–2% were launched, forming a constellation with rapid revisit capability. The hyperspectral imager on the domestically produced Gaofen-5 02 satellite, targeting typical methane super-emission sources in China and the United States, as well as methane point sources in coal mines in Shanxi Province, can quantify methane point source emissions of approximately 700.00–16000 kg h⁻¹. In addition, multispectral instruments such as Sentinel-2, Landsat, and WorldView-3 are also capable of detecting and quantifying ultra-large methane emission point sources.

△Permian Basin (Texas and New Mexico), July 2020

Satellite observations of atmospheric methane

Current satellite spectrometers have detection thresholds ranging from 100 to 10,000 kg h⁻¹, enabling them to monitor large methane emission point sources, discover previously unknown emission sources, and quantify total emissions. With the expansion of methane point source detection satellite constellations, including the GHGSat and Carbon Mapper constellations, and the upcoming methane satellite constellation from CAS Xiguang, the next few years will see a significant increase in the integrity, spatial coverage, and revisit frequency of point source observation systems through intensive observations, contributing to a better understanding of the intermittent nature of methane emissions.