Investigating NO2 processing in power plant plumes from TROPOMI

The divergence, i.e. the spatial derivative of the horizontal flux, yields the local balance of sources of sinks. Strong positive divergence is observed for (and allows to quantify) NOx emissions from point sources like power plants. Within the downwind plume, NO2 changes due to (a) further NO to NO2 conversion (NO2 source, positive divergence) and (b) NO2 reaction with OH (NO2 sink, negative divergence). In this study we aim to disentangle and quantify these competing effects based on the divergence of the observed NO2 flux. We focus on large and isolated power plants where additional sources are negligible. Goal is to determine the time scales for the NO to NO2 conversion and the NO2 lifetime for power plant plumes.