A031-0006
Variability of nitrogen oxide emission fluxes and lifetimes estimated by Sentinel-5P TROPOMI observations
Variability of nitrogen oxide emission fluxes and lifetimes estimated by Sentinel-5P TROPOMI observations
Tuesday, 8 December 2020
Poster
Abstract:
Observations of the instrument TROPOMI on the Sentinel-5 Precursor satellite provide measurements of nitrogen dioxide (NO2) at city level and allow quantifying variability of nitrogen oxide (NOx) emissions and lifetimes on a seasonal and daily basis.
To quantify nitrogen oxide emissions and lifetimes with their high variability in space and time, satellite data is especially suited as it provides daily global coverage and a large number of measurements. In this study two years of Sentinel-5P TROPOMI NO2 data with a spatial resolution of up to 3.5 km x 5.5 km together with ECMWF ERA5 wind data is analyzed. The NO2 satellite data around the source are linked to the ERA5 wind data and rotated to a uniform wind direction to get clear NO2 plumes. Out of these two-dimensional maps of the mean NO2 distribution, one dimensional line densities are calculated by integration across wind direction. Lifetimes and emission fluxes are calculated for up to 45 different NOx sources represented by cities and power plants distributed over the world.
Calculated emissions compared to bottom-up emission inventories show significantly lower values but are in good agreement with other studies which analyzed emissions using TROPOMI data. Separation into seasons shows a seasonal dependence of emissions with in general the highest emissions during winter, except for cities in Saudi Arabia. The investigation of the latitudinal dependence of the NOx lifetime shows an increase in lifetime in correlation to an increase in latitude but only a weak seasonal dependence for separation into seasons. Weekday variability of emissions is found with weekend-to-weekday ratios of up to 0.5 but with a high variability for the different source regions. Emission comparisons of pre Covid-19 times and the lockdown period during Covid-19 show strong reductions in NOx emissions during the lockdown.
To quantify nitrogen oxide emissions and lifetimes with their high variability in space and time, satellite data is especially suited as it provides daily global coverage and a large number of measurements. In this study two years of Sentinel-5P TROPOMI NO2 data with a spatial resolution of up to 3.5 km x 5.5 km together with ECMWF ERA5 wind data is analyzed. The NO2 satellite data around the source are linked to the ERA5 wind data and rotated to a uniform wind direction to get clear NO2 plumes. Out of these two-dimensional maps of the mean NO2 distribution, one dimensional line densities are calculated by integration across wind direction. Lifetimes and emission fluxes are calculated for up to 45 different NOx sources represented by cities and power plants distributed over the world.
Calculated emissions compared to bottom-up emission inventories show significantly lower values but are in good agreement with other studies which analyzed emissions using TROPOMI data. Separation into seasons shows a seasonal dependence of emissions with in general the highest emissions during winter, except for cities in Saudi Arabia. The investigation of the latitudinal dependence of the NOx lifetime shows an increase in lifetime in correlation to an increase in latitude but only a weak seasonal dependence for separation into seasons. Weekday variability of emissions is found with weekend-to-weekday ratios of up to 0.5 but with a high variability for the different source regions. Emission comparisons of pre Covid-19 times and the lockdown period during Covid-19 show strong reductions in NOx emissions during the lockdown.