Point sources, such as fossil fuel burning power plants, steel production plants and refineries are key emitters of CO2. Because they can undergo large variations in emissions over time due to, for example, changing economic conditions, the monitoring of their emissions, especially in the context of recent climate treaties, is important. Europe, in particular, is developing a system to support Monitoring, Reporting and Verification (MRV) of various CO2 sources based on a combination of space-borne and ground-based measurements.
CO2 flux inversion approaches that rely on space data are currently, and also in the near future, based on low-orbit polar satellite instruments that provide only episodic sampling of CO2 plumes. These snapshots correspond only to a representation of transport during the overpass of the satellite. Under turbulent conditions, the plumes show a strong temporal variability and their shape differs from the generally assumed Gaussian plume shape.
In this work we use the EULAG LES model to simulate the spatio-temporal variability of the CO2 plume in the vicinity of strong sources. The realism of the model simulated transport is evaluated against measurement data from the CoMet campaign on 7 June 2018 over the Bełchatów power plant in central Poland. Next the impact of the LES simulated variability on two top-down flux retrieval methods is analysed. For the Optimal Estimation Method (OEM), we provide a preliminary quantification of the relative model error due to its inherent inability to reproduce the stochastic features of turbulent transport. For the Mass Balance method, we analyse the impact of the non-Gaussian shape and of the presence of pockets (or puffs) with high CO2, on the individual line densities at various distances from the source. Given the high variability in our line density estimates, while depending on the swath width and the part of the plume being imaged, the mean flux values retrieved from a simple overpass will be affected.
The work presented in this report is issued from work in progress. The perspectives are provided in a dedicated section.