Ground-based investigation of HO<sub><i>x</i></sub> and ozone chemistry in biomass burning plumes in rural Idaho

Abstract. Ozone (O3), a potent greenhouse gas that is detrimental to human health, typically found in elevated concentrations within biomass burning (BB) smoke plumes. The radical species OH, HO2, and RO2 (known collectively as ROx) have central roles the formation of secondary pollutants including O3 but are poorly characterized for BB We present measurements total peroxy ([XO2] ≡ [HO2] + [RO2]) additional trace-gas particulate matter from McCall, Idaho, during August 2018. There were five distinct periods which impacted this site. During events, enhanced, evident by ozone enhancement ratios (ΔO3/ΔCO) ranged up 0.06 ppbv ppbv−1. [XO2] was similarly some events. Overall, instantaneous production rates (P(O3)) minimally presence [NOx] enhancements minimal. Measured XO2 compared zero-dimensional box modeling results evaluate Master Chemical Mechanism (MCM) GEOS-Chem mechanisms overall influence. models consistently overestimated with base MCM predictions high an average 28 % 20 %, respectively. One period influence had measured 15 pptv not reflected model output, likely due unmeasured HOx sources. To best our knowledge, first study featuring measurements.