Relationship between deseasonalised annual OMI NO₂ VCD and regional annual oil or gas production. Deseasonalised annual OMI NO₂ VCD (solid lines), with 95^th percentile confidence bounds (dashed lines), and regional annual oil or gas production (bars) are shown. Note that annual OMI-NO₂ is plotted with different axis ranges to make the relationship more apparent. DOI: https://doi.org/10.1525/elementa.259.f5