부산대학교 도서관

We present a comparison of fast-response instruments installed onboard the NASA DC-8 aircraft that measured nitrogen oxides (NO and NO 2), nitrous acid (HONO), total reactive odd nitrogen (measured both as the total (NO y) and from the sum of individually measured species (Σ NO y)), and carbon monoxide (CO) in the troposphere during the 2019 Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) campaign. By targeting smoke from summertime wildfires, prescribed fires, and agricultural burns across the continental United States, FIREX-AQ provided a unique opportunity to investigate measurement accuracy in concentrated plumes where hundreds of species coexist. Here, we compare NO measurements by chemiluminescence (CL) and laser-induced fluorescence (LIF); NO 2 measurements by CL, LIF, and cavity-enhanced spectroscopy (CES); HONO measurements by CES and iodide-adduct chemical ionization mass spectrometry (CIMS); and CO measurements by tunable diode laser absorption spectrometry (TDLAS) and integrated cavity output spectroscopy (ICOS). Additionally, total NO y measurements using the CL instrument were compared with Σ NO y (= NO + NO 2 + HONO + nitric acid (HNO 3) + acyl peroxy nitrates (APNs) + submicrometer particulate nitrate (p NO 3)). Other NO y species were not included in Σ NO y as they either contributed minimally to it (e.g., C 1 –C 5 alkyl nitrates, nitryl chloride (ClNO 2), dinitrogen pentoxide (N 2 O 5)) or were not measured during FIREX-AQ (e.g., higher oxidized alkyl nitrates, nitrate (NO 3), non-acyl peroxynitrates, coarse-mode aerosol nitrate). The aircraft instrument intercomparisons demonstrate the following points: (1) NO measurements by CL and LIF agreed well within instrument uncertainties but with potentially reduced time response for the CL instrument; (2) NO 2 measurements by LIF and CES agreed well within instrument uncertainties, but CL NO 2 was on average 10 % higher; (3) CES and CIMS HONO measurements were highly correlated in each fire plume transect, but the correlation slope of CES vs. CIMS for all 1 Hz data during FIREX-AQ was 1.8, which we attribute to a reduction in the CIMS sensitivity to HONO in high-temperature environments; (4) NO y budget closure was demonstrated for all flights within the combined instrument uncertainties of 25 %. However, we used a fluid dynamic flow model to estimate that average p NO 3 sampling fraction through the NO y inlet in smoke was variable from one flight to another and ranged between 0.36 and 0.99, meaning that approximately 0 %–24 % on average of the total measured NO y in smoke may have been unaccounted for and may be due to unmeasured species such as organic nitrates; (5) CO measurements by ICOS and TDLAS agreed well within combined instrument uncertainties, but with a systematic offset that averaged 2.87 ppbv; and (6) integrating smoke plumes followed by fitting the integrated values of each plume improved the correlation between independent measurements. [ABSTRACT FROM AUTHOR]