New techniques to quantify methane point sources using multispectral data from Copernicus Sentinel-2 are instrumental for global monitoring of large point emissions in oil and gas production regions.
When considering the various kinds of greenhouse gas emissions that are at the heart of climate change, methane (CH4) is the second most important gas emitted by humans following carbon dioxide (CO2), having a global warming potential 86 times higher than carbon dioxide over a span of 20 years [1]. This fact makes our need to understand and map methane emissions a priority for researchers interested in climate change.
Sectors such as oil and gas, production infrastructure and coal mines produce between 30% and 42% of all greenhouse gas emissions, including methane [1]. These facilities normally emit methane gas from small source areas, referred to as “point source emissions”.
By detecting and mitigating a large fraction of these point emission sources, a meaningful reduction in the outflow of greenhouse gasses into our atmosphere is achievable.
Typically, satellites identify methane by looking at subtle variations in backscattered solar radiation in the short-wave infrared (SWIR) spectral region, that can be linked to methane emissions.
Missions that utilise this methodology are well established and robust and have successfully been used to map methane emissions at both regional and global spatial scales over long periods of time.
Multispectral satellites acquire data in multiple wavebands – say from eight to 20 wavebands - whereas hyperspectral satellites acquire data in the order of hundreds of different wavebands.
The Italian-led hyperspectral mission PRISMA can resolve fine methane absorption features in the SWIR, typically providing a detection limit from 100 to 500 kgh−1.
One pitfall of hyperspectral missions, however, is a low revisit frequency that limits their usefulness for monitoring on a global scale.
In contrast, multispectral missions, such as Copernicus Sentinel-2 and Landsat provide a unique combination of global coverage, detailed instrument characterisation and a revisit frequency of five days, making their technology invaluable to researchers looking to map methane point-source emissions.
The Sentinel-2 missions of the European Union’s Copernicus Programme, launched in 2015 and 2017 respectively, provide continuous monitoring of terrestrial surfaces and coastal waters on a global scale. Both satellites contain multispectral imaging technology that allow researchers to map data in the visible and near-infrared parts of the spectrum, at spatial resolutions of 10, 20 or 60 m.
New research published in the journal of Atmospheric Measurement Techniques has shown a methodology to use Copernicus Sentinel-2 data to detect large point source methane plumes with a detection limit in the range of 1000 to 2000 kgh
Javier Gorroño, from the Research Institute of Water and Environmental Engineering (IIAMA) at the Universitat Politècnica de València, Spain, says, “Despite its limited spectral design, the Sentinel-2 mission can support the detection of large methane point source emissions with global coverage and high revisit frequency, thanks to spectral coverage of methane absorption lines in the SWIR.”
Validation of Sentinel-2 methane retrieval algorithms was achieved by applying the methodology to simulated methane point sources emissions in areas of known oil and gas activity in Turkmenistan (Korpeje), Algeria (Hassi Messaoud) and USA (the Permian Basin).
The researchers scaled these simulated methane emissions at varying levels of methane flux rate, in order to better understand the range of detection limits possible with Copernicus Sentinel-2 data.
Validation of Sentinel-2 methane retrieval algorithms in this way is instrumental in accelerating the development of a systematic and global monitoring system for methane point sources.
Ultimately, theoretical research of this kind can be applied to develop new and comprehensive global systems for monitoring methane point sources. In doing so, we arm ourselves with a new understanding of our climate that can be used to create a safer and healthier world for generations to come.
About the Copernicus Sentinels
The Copernicus Sentinels are a fleet of dedicated EU-owned satellites, designed to deliver the wealth of data and imagery that are central to the European Union's Copernicus environmental programme.
The European Commission leads and coordinates this programme, to improve the management of the environment, safeguarding lives every day. ESA is in charge of the space component, responsible for developing the family of Copernicus Sentinel satellites on behalf of the European Union and ensuring the flow of data for the Copernicus services, while the operations of the Copernicus Sentinels have been entrusted to ESA and EUMETSAT.
Did you know that?
Earth observation data from the Copernicus Sentinel satellites are fed into the Copernicus Services. First launched in 2012 with the Land Monitoring and Emergency Management services, these services provide free and open support, in six different thematic areas.
The Copernicus Marine Environment Monitoring Service (CMEMS) provides regular and systematic reference information on the physical and biogeochemical state, variability and dynamics of the ocean and marine ecosystems for the global ocean and the European regional seas.
References:
[1] Gorroño, J. et al: “Understanding the potential of Sentinel-2 for monitoring methane point emissions” Atmos. Meas. Tech., 16, 89–107, 2023.
[2] High-resolution methane mapping with hyper and multispectral data (HiResCH4).