Recommendation of a consensus value of the ozone absorption cross-section at 253.65 nm based on a literature review J. Hodges, J. Viallon, P. Brewer, B. Drouin, V. Gorshelev, C. Janssen, S. Lee, A. Possolo, M. Smith, J. Walden, et al. To cite this version: J. Hodges, J. Viallon, P. Brewer, B. Drouin, V. Gorshelev, et al.. Recommendation of a consensus value of the ozone absorption cross-section at 253.65 nm based on a literature review. Metrologia, IOP Publishing, 2019, 56 (3), pp.034001. 10.1088/1681-7575/ab0bdd. hal-02108262 HAL Id: hal-02108262 https://hal.sorbonne-universite.fr/hal-02108262 Submitted on 24 Apr 2019 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Metrologia PAPER • OPEN ACCESS Recommendation of a consensus value of the ozone absorption cross- section at 253.65 nm based on a literature review To cite this article: J T Hodges et al 2019 Metrologia 56 034001 View the article online for updates and enhancements. This content was downloaded from IP address 134.157.80.196 on 24/04/2019 at 08:46 IOP Metrologia Metrologia Metrologia Metrologia 56 (2019) 034001 (12pp) https://doi.org/10.1088/1681-7575/ab0bdd 56 Recommendation of a consensus value 2019 of the ozone absorption cross-section © 2019 BIPM & IOP Publishing Ltd at 253.65 nm based on a literature review MTRGAU J T Hodges1 , J Viallon2,10 , P J Brewer3 , B J Drouin4, V Gorshelev5, C Janssen6 , S Lee7 , A Possolo1 , M A H Smith8 , J Walden9 034001 and R I Wielgosz2 1 National Institute of Standards and Technology (NIST), Gaithersburg, MD, United States of America J T Hodges et al 2 Bureau International des Poids et Mesures (BIPM), Sèvres, France 3 National Physical Laboratory (NPL), Teddington, Middlesex, United Kingdom 4 Jet Propulsion Laboratory, NASA, California Institute of Technology, Pasadena, CA, United States of America 5 Institute of Environmental Physics, Bremen University, Bremen, Germany 6 Printed in the UK LERMA-IPSL, Sorbonne Université, Observatoire de Paris, PSL Université, CNRS, Paris, France 7 Korea Research Institute of Standards and Science (KRISS), Daejeon, Republic of Korea 8 NASA Langley Research Center, Hampton, VA, United States of America MET 9 Finnish Meteorological Institute (FMI), Helsinki, Finland E-mail: [email protected] (J Viallon) 10.1088/1681-7575/ab0bdd Received 19 October 2018, revised 14 February 2019 Accepted for publication 1 March 2019 Paper Published 4 April 2019 Abstract 1681-7575 A detailed review and analysis of literature values for the absorption cross-section of ozone at room temperature at the mercury-line wavelength (253.65 nm, air) is reported. Data from fourteen independent sets of measurements spanning the years 1959–2016 were considered. The present analysis is based upon a revised assessment of all Type A and Type B uncertainty 3 components for each previously reported cross-section. A consensus value for the absorption cross-section of 1.1329(35) × 10−17 cm2 molecule−1 is recommended based on statistical analysis of the weighted data. This new cross-section value is 1.23% lower and its uncertainty sixfold smaller than the uncertainty of the conventionally accepted reference value reported by Hearn (1961 Proc. Phys. Soc. 78 932–40). Keywords: ozone, absorption cross-section, reference data, troposphere S Supplementary material for this article is available online (Some figures may appear in colour only in the online journal) Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. 10 Author to whom any correspondence should be addressed. 1681-7575/19/034001+12$33.00 1 © 2019 BIPM & IOP Publishing Ltd Printed in the UK Metrologia 56 (2019) 034001 J T Hodges et al 1. Introduction reasons, Bass and Paur recognized that a mercury-vapor lamp would make a good light source for their standard ozone pho- Gas phase ozone (O3) plays a key role in the chemical and tometer. After following the United States Environmental radiative equilibrium of the Earth’s atmosphere because of Protection Agency (U.S. EPA) guide on ozone calibrations its high chemical reactivity and intense absorption spectrum. developed in 1979 [2], they adopted the ozone absorption Ozone occurs naturally in both the stratosphere and the tro- cross-section at the mercury line as a reference value. In posphere. In the stratosphere it is produced by a reaction of 1961, this cross-section was measured by Hearn to be equal −17 2 −1 atomic oxygen with O2 and provides an effective screen for to 1.147 × 10 cm molecule with a reported relative organisms from harmful ultraviolet (UV) solar radiation. standard uncertainty of 1.4% [3]. Bass and Paur also meas- While the broadband spectroscopic features in the UV and ured the absorption cross-section of ozone over an extended visible (VIS) spectral regions absorb incoming solar radia- spectral region relative to this reference value [4, 5]. tion, the narrowband rotation-vibration features spanning the Since the development of the NBS SRP, more than 60 of infrared (IR) provide the long-wavelength feedback that make these photometers have been constructed by the NIST and ozone an important greenhouse gas. now serve as primary standards for national and international In the troposphere, ground-level ozone is a harmful pol- ozone monitoring networks, such as the WMO global atmos- lutant that is caused by the photochemical decomposition of phere watch (GAW) Programme [6, 7]. Several realizations of nitrogen oxides and volatile organic compounds. Technology the NIST SRP are maintained at the International Bureau of for accurately monitoring local ozone concentrations in urban Weights and Measures (French acronym BIPM), one of which settings is required to identify sources and locations of ozone, is the reference for international comparisons of ozone stand- to ensure compliance with local emissions regulations, and to ards coordinated by the BIPM [8]. In practice, SRPs main- notify communities when unsafe conditions occur. There are tained by State Parties to the Metre Convention are regularly also numerous long-range (spatial and temporal) observations compared within the framework of the international compar- from aircraft, balloon-borne probes and satellites, which pro- ison BIPM.QM-K1 (See for example [9]). vide spatiotemporal information on the global status of ozone Meanwhile, results of several studies have called into ques- and which require accurate spectroscopic properties of ozone. tion the confidence in Hearn’s conventionally accepted value Most quantitative measurements of ozone concentration in for the ozone 253.65 nm absorption cross-section. Given that the laboratory and field involve linear absorption spectroscopy ozone is highly reactive, the measured ozone concentration methods. Of the many ozone light absorption features from in the experiments of Bass and Paur [4] and others discussed the UV to IR, the Hartley UV band near 255 nm provides one below were susceptible to difficult-to-assess uncertainty asso- of the strongest absorption signatures, making it attractive for ciated with sample impurity, leading to a potential bias in ground-level ozone concentration retrievals where low detec- the reference absorption cross-section. To quantify this bias, tion limits (mole fractions in air at the nmol mol−1 level) are SRP-based UV absorption measurements were compared to required. Relatively inexpensive and rugged mercury-vapor independent determinations of ozone concentration based lamps are used as light sources in closed-path absorption on gas phase titration (GPT). The latter technique involves spectrometers for measuring ground-level ozone in many lab- reacting ozone in air with nitrogen monoxide (NO) and oratory and field applications. These lamps emit incoherent measuring either the loss of NO or the gain of the reaction light in the UV and VIS regions at numerous discrete wave- product, nitrogen dioxide (NO2) to deduce the ozone concen- lengths, with by far the most intense emission occurring at the tration in the sample. In two independent realizations of the wavelength 253.65 nm (in air) [1], which corresponds to the GPT method, a 2%–3% bias in the ozone reference absorp- 1 3 6 S0 ← 6 P1 inter-combination band electronic transition of tion cross-section was observed by the National Institute for gaseous elemental mercury (Hg0). Coincidently, this mercury Environmental Studies of Japan (NIES) [10] and the BIPM transition occurs near the wavelength maximum of the ozone [11], with the two GPT methods reporting higher ozone con- Hartley band, thus making mercury-vapor lamps attractive centrations than the SRP measurements. The most likely for compact UV absorption photometers that measure ozone. explanation was a systematic deviation in the ozone reference Therefore, direct absorption methods employed by these mer- absorption cross-section, which usually represents the major cury-lamp photometers require knowledge of the 253.65 nm uncertainty component in ozone measurements based on UV absorption cross-section to provide ozone concentration photometry. derived from measurements of sample absorbance and optical The 253.65 nm cross-section is also relevant to ground- pathlength. Thus, when using mercury-lamp photometry, the and satellite-based measurements of atmospheric ozone using minimum combined standard uncertainty in the measured broadband spectroscopic methods operating throughout the ozone concentration can be no smaller than that of the ozone UV, VIS and IR spectral regions, and for which accurate absorption cross-section at 253.65 nm.