Parameterizations of US wildfire and prescribed fire emission ratios and emission factors based on FIREX-AQ aircraft measurements

The sum of primary NMOG EFs correlates to MCE with an R 2 of 0.68 and a slope of - 296 +/- 51 g kg - 1 , consistent with previous studies. The sum of the NMOG mixing ratios correlates well with CO with an R 2 of 0.98 and a slope of 137 +/- 4 ppbv of NMOGs per parts per million by volume (ppmv) of CO, demonstrating that primary NMOG emissions can be estimated from CO. Individual nitrogen-containing species correlate better with NO 2 , NO y , and black carbon than with CO.

More than half of the NO y in fresh plumes is NO 2 with an R 2 of 0.95 and a ratio of NO 2 to NO y of 0.55 +/- 0.05 ppbv ppbv - 1 , highlighting that fast photochemistry had already occurred in the sampled fire plumes. The ratio of NO y to the sum of NMOGs follows trends observed in laboratory experiments and increases exponentially with MCE, due to increased emission of key nitrogen species and reduced emission of NMOGs at higher MCE during flaming combustion.

These parameterizations will provide more accurate boundary conditions for modeling and satellite studies of fire plume chemistry and evolution to predict the downwind formation of secondary pollutants, including ozone and secondary organic aerosol.