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) NO_x 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.