Madrid Methane Remote Sensing: first results of a landfill field campaign

Methane (CH₄) is known to be one of the most potent greenhouse gases (GHGs) and it plays a key role in climate change due to its high warming potential. It is of both natural and anthropogenic origin. The main anthropogenic emissions of CH₄ come from agriculture, fossil fuels (gas, oil, coal), landfills and wastewater treatment plants.

Two of the largest landfills in Europe are the Pinto and Technology Park Valdemingómez landfills in Spain. Both landfills, which are only a couple of kilometres apart, are located in the south of Madrid metropolitan area. These sorts of landfills are considered extended sources of GHGs due to their surface area, which spans a few square kilometres. Understanding the emissions from such landfills is critical to accurately assess and mitigate their impact on climate change.

In summer 2024, a ground-based remote sensing field campaign was carried out around these two landfills to evaluate the capabilities and limitations of the deployed instruments, which were two shortwave hyperspectral infrared cameras mounted on tripods scanning the horizon. Such a camera has previously been used for detecting emissions of GHGs from point sources such as a power plant (Knapp et al., 2024). The campaign in Madrid aimed at testing the cameras’ capabilities regarding extended sources of CH₄ such as landfills. During the campaign, these ground-based measurements were complemented by observations from different satellites (GHGSat, EnMAP and TROPOMI-SP5).

This work will describe the field campaign and retrieval techniques as well as present first results of the observations of the campaign. Moreover, an extended study of TROPOMI’s observations of the target landfills will be presented (2019 - 2024), comparing inferred CH₄ emission rates to previous studies and to values reported to PRTR-Spain (Spanish Register of Emissions and Pollutant Sources).