AUTHOR=Hakkarainen Janne , Ialongo Iolanda , Koene Erik , Szeląg Monika E. , Tamminen Johanna , Kuhlmann Gerrit , Brunner Dominik TITLE=Analyzing Local Carbon Dioxide and Nitrogen Oxide Emissions From Space Using the Divergence Method: An Application to the Synthetic SMARTCARB Dataset JOURNAL=Frontiers in Remote Sensing VOLUME=3 YEAR=2022 URL=https://www.frontiersin.org/journals/remote-sensing/articles/10.3389/frsen.2022.878731 DOI=10.3389/frsen.2022.878731 ISSN=2673-6187 ABSTRACT=

Since the Paris Agreement was adopted in 2015, the role of space-based observations for monitoring anthropogenic greenhouse gas (GHG) emissions has increased. To meet the requirements for monitoring carbon dioxide (CO₂) emissions, the European Copernicus programme is preparing a dedicated CO₂ Monitoring (CO2M) satellite constellation that will provide CO₂ and nitrogen dioxide (NO₂) observations at 4 km² resolution along a 250 km wide swath. In this paper, we adapt the recently developed divergence method to derive both CO₂ and nitrogen oxide (NO_x) emissions of cities and power plants from a CO2M satellite constellation by using synthetic observations from the COSMO-GHG model. Due to its long lifetime, the large CO₂ atmospheric background needs to be removed to highlight the anthropogenic enhancements before calculating the divergence. Since the CO₂ noise levels are large compared to the anthropogenic enhancements, we apply different denoising methods and compare the effect on the CO₂ emission estimates. The annual NO_x and CO₂ emissions estimated from the divergence maps using the peak fitting approach are in agreement with the expected values, although with larger uncertainties for CO₂. We also consider the possibility to use co-emitted NO_x emission estimates for quantifying the CO₂ emissions, by using source-specific NO_x-to-CO₂ emission ratios derived directly from satellite observations. In general, we find that the divergence method provides a promising tool for estimating CO₂ emissions, alternative to typical methods based on inverse modeling or on the analysis of individual CO₂ plumes.