Metrology for comparable and trustworthy greenhouse gas remote sensing datasets

Greenhouse gases (GHG) such as carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) from manmade activities are driving climate change. Invaluable information on their sources, movements, and sinks are provided by satellites orbiting the Earth equipped with spectrometers. This information inputs into mitigation strategies, policy-making, negotiations on emission levels, emission verification, and carbon taxing.

Recently, it has been shown that atmospheric water can interfere with spectroscopic analysis of many GHGs, decreasing the spectral line intensity of the data. A greater knowledge of this effect is increasingly important for GHG observations from current satellite missions such as OCO-2, GOSAT-2 or up and coming ones such as MicroCarb, MethaneSAT, and CO2M. These need traceable spectroscopic information to link them with surface in-situ observation networks, particularly for the estimation of CO₂ and CH₄ sources and sinks where the required precision and accuracy of the observations is increasingly stringent at 0.1 %-0.24 %.

This project will provide spectroscopic equivalence and comparability among various GHG satellite observations, both in Europe and internationally, by greatly improving the accuracy of spectral line data for CO₂, CH₄, N₂O, oxygen and water. This will be validated through inter-laboratory comparisons with different types of spectrophotometers and used to calibrate GHG satellite missions, combining observations from these with balloon and ground-based data.

The work will establish SI traceability for satellite monitoring of GHG levels, providing an accurate quantification of their sources and sinks. This in turn will enable policy makers to make more informed decisions on climate change mitigation plans, benefiting the environment and our society.