부산대학교 도서관

We use observations of acyl peroxynitrates (PANs) from the Cross‐Track Infrared Sounder (CrIS) to investigate PANs over the western U.S. during the summer 2018 wildfire season. This period coincides with the Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption, and Nitrogen (WE‐CAN). When combined with favorable background conditions, the resolution and sensitivity of CrIS is sufficient to observe the production of PANs in smoke plumes. CrIS PANs normalized excess mixing ratios with respect to CO (NEMRs) in the Pole Creek Fire increase from 0.2% to 0.4% within 3–4 hr of physical aging, consistent with in situ NEMRs. CrIS is also able to detect PANs enhancements in plumes that have been transported hours to days downwind. On average for summer 2018, 19–56% of PANs in the free troposphere during the afternoon over the western U.S. can be attributed to smoke. Plain Language Summary: Wildfire smoke contains nitrogen compounds, such as nitrogen oxide radicals, that participate in ozone chemistry and degrade air quality. Acyl peroxynitrates, also known as PANs, are formed rapidly in wildfire plumes and serve as temporary reservoirs for nitrogen oxide radicals. At colder temperatures, PANs can transport nitrogen oxides very long distances before releasing them again to the atmosphere. Here we discuss the detection of PANs in wildfire smoke using new measurements from the Cross‐Track Infrared Sounder (CrIS). We find that CrIS is able to detect high concentrations of PANs in smoke plumes from fast‐growing fires. The instrument is also able to detect the chemical production of PANs within a given smoke plume and the production rates are comparable with aircraft observations during the Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption, and Nitrogen (WE‐CAN). Our results highlight the importance of wildfires as a source of PANs in the midlatitudes and show the potential of satellite retrievals to compliment campaign‐based observations of PANs. Key Points: CrIS is able to detect PANs and CO enhancements in smoke plumes from many wildfires during the 2018 wildfire seasonWe estimate that the average contribution from wildfire to tropospheric PANs over the western U.S. is 19–56% during the 2018 wildfire seasonNear source PANs photochemical production rates can be observed using CrIS measurements of PANs and CO [ABSTRACT FROM AUTHOR]