Comparison of ultraviolet absorbance and NO-chemiluminescence for ozone measurement in wildfire plumes at the Mount Bachelor Observatory. (October 2017)

• Record Type: Journal Article
• Authors: Gao, Honglian; Jaffe, Daniel A.
• Is Part Of: Atmospheric environment. Volume 166(2017)
• Page Start: 224
• Page End: 233
• Publication Date: 2017-10
• Subjects: Ozone -- UV photometer -- NO-chemiluminescence -- Wildfire; Air -- Pollution -- Periodicals; Air -- Pollution -- Meteorological aspects -- Periodicals; 551.51
• DOI: 10.1016/j.atmosenv.2017.07.007
• Languages: English
• ISSNs: 1352-2310

Abstract

Abstract: The goal of this paper is to evaluate the accuracy of the commonly used ozone (O3 ) instrument (the ultraviolet (UV) photometer) against a Federal Reference Method (Nitric Oxide –chemiluminescence) for ozone measurement in wildfire smoke plumes. We carried out simultaneous ozone measurement with two UV O3 photometers and one nitric oxide–chemiluminescence (NO-CL) ozone detectors during wildfire season (Aug. 1–Sept. 30) in 2015 at the Mount Bachelor Observatory (MBO, 2763 m above mean sea level, Oregon, USA). The UV O3 shows good agreement and excellent correlation to NO-CL O3, with linear regression slopes close to unity and R 2 of 0.92 for 1-h average data and R 2 of 0.93 for O3 daily maximum 8-h average (MDA8). During this two-month period we identified 35 wildfire events. Ozone enhancements in those wildfire plumes measured by NO-CL O3 and UV O3 monitors also show good agreement and excellent linear correlation, with a slope and R 2 of 1.03 and 0.86 for O3 enhancements (ΔO3 ) and 1.00 and 0.98 for carbon monoxide (CO)-normalized ozone enhancement ratios (ΔO3 /ΔCO), respectively. Overall, the UV O3 was found to have a positive bias of 4.7 ± 2.8 ppbv compared to the NO-CL O3 . The O3 bias between NO-CL O3 and UV O3 is independent of wildfire plume tracers such as CO, particulate matter (PM1 ), aerosol scattering, and ultrafine particles. The results demonstrate that the UV O3 absorbance method is reliable, even in highly concentrated wildfire plumes. Highlights: UV is consistent with NO-CL in mountaintop O3 measurement. UV agrees with NO-CL in O3 enhancement during 35 wildfire events. The UV O3 photometer is reliable in aged wildfire plumes.