Evaluation of satellite-derived NOx emissions over Europe

Nitrogen oxides (NO_x) emissions play an important role in air quality, the nitrogen cycle, and as precursor for climate gasses. The most important sources of NO_x emissions are fossil fuel burning (industry and traffic) and the release from soil.

With the inversion algorithm DECSO (Daily Emissions Constrained by Satellite Observations) we derive quantitative NO_x emissions on a 5 to 20 km resolution from TROPOMI (on Sentinel 5p) observations of NO₂, taking advantage of the fine spatial resolution (5 x 3.5 km) of the TROPOMI instrument. DECSO is a full inversion algorithm based on data assimilation of satellite observation and the Chemical-transport model CHIMERE. For the data assimilation a Kalman Filter technique is used. For the inversion no apriori information of the NO_x emissions is needed and for this reason new sources can be detected. In the postprocessing we use the seasonal cycle to distinct between soil emissions (having strong seasonal cycle with summer peak) and anthropogenic emissions (having low variability over the year).

To assess the quality of satellite-derived NO_x emissions on various scales, i.e. national, regional, city and points-sources, they are compared to various bottom-up inventories. For bottom-up emissions we selected NEC (National Emission Ceilings Directive inventory), LRTAP (LRTAP convention data), the CAMS (Copernicus Atmosphere Monitoring Service) regional anthropogenic emission database and the high-resolution emission inventory HERMES (High-Elective Resolution Modelling Emission System) for Catalonia. Detailed results will be shown, including the spatial and temporal variation per emission category.