Daytime Oxidized Reactive Nitrogen Partitioning in Western U.S. Wildfire Smoke Plumes

The Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption, and Nitrogen (WE-CAN) deployed the NSF/NCAR C-130 aircraft in summer 2018 across western U.S. to sample wildfire smoke during its first days of atmospheric evolution. We present a summary subset reactive oxidized nitrogen species (NOy) plumes sampled pseudo-Lagrangian fashion. Emissions oxides (NOx = NO + NO2) nitrous acid (HONO) are rapidly converted more forms. Within 4 h, ∼86% ΣNOy is form peroxy acyl nitrates (PANs) (∼37%), particulate nitrate (pNO3) (∼27%), gas-phase organic (Org N(g)) (∼23%). average e-folding time distance NOx ∼90 min ∼40 km, respectively. Nearly no enhancements nitric (HNO3) were observed fashion, implying HNO3-limited ammonium (NH4NO3) formation, with one notable exception that we highlight as case study. also summarize partitioning NOy all samples intercepted WE-CAN. In above 3 km sea level (ASL), contributions PANs pNO3 increase altitude. WE-CAN from multiple fires mixed anthropogenic emissions over California Central Valley. distinguish where appear lead an abundances by factor four contribute additional PAN formation.