Comparison of nitrous oxide (N<sub>2</sub>O) analyzers for high-precision measurements of atmospheric mole fractions

Abstract

Abstract.Over the last few decades, in situ measurements of atmospheric N 2 O mole fractions have been performed using gas chromatographs (GCs) equipped with electron capture detectors. This technique, however, becomes very challenging when trying to detect the small variations of N 2 O as the detectors are highly nonlinear and the GCs at remote stations require a considerable amount of maintenance by qualified technicians to maintain good short-term and long-term repeatability. With new robust optical spectrometers now available for N 2 O measurements, we aim to identify a robust and stable analyzer that can be integrated into atmospheric monitoring networks, such as the Integrated Carbon Observation System (ICOS). In this study, we present the most complete comparison of N 2 O analyzers, with seven analyzers that were developed and commercialized by five different companies. Each instrument was characterized during a time period of approximately 8 weeks. The test protocols included the characterization of the short-term and long-term repeatability, drift, temperature dependence, linearity and sensitivity to water vapor. During the test period, ambient air measurements were compared under field conditions at the Gif-sur-Yvette station. All of the analyzers showed a standard deviation better than 0.1 ppb for the 10 min averages. Some analyzers would benefit from improvements in temperature stability to reduce the instrument drift, which could then help in reducing the frequency of calibrations. For most instruments, the water vapor correction algorithms applied by companies are not sufficient for high-precision atmospheric measurements, which results in the need to dry the ambient air prior to analysis.

A top-down approach of sources and non-photosynthetic sinks of carbonyl sulfide from atmospheric measurements over multiple years in the Paris region (France)

“…for 6 months in 2015-2016 covering winter and spring pollution episodes. Before being deployed at the SAC site, the specifications of our mini QCL instrument were evaluated in the laboratory following the standardized testing protocols designed for analyzers measuring H 2 O, CO 2 , CH 4 , CO and N 2 O in the framework of the ICOS (Integrated Carbon Observation System) European Infrastructure [19][20]. We determined (1) the continuous measurement repeatability (CMR) for COS, (2) the optimal averaging time estimated by using Allan standard deviation plots, (3) the stabilization time, (4) the short-term repeatability (STR), (5) the long-term repeatability (LTR, in two different ways), (6) the temperature dependence, (7) the water vapor sensitivity, (8) the linearity, and defined a calibration strategy.…”

“…We determined (1) the continuous measurement repeatability (CMR) for COS, (2) the optimal averaging time estimated by using Allan standard deviation plots, (3) the stabilization time, (4) the short-term repeatability (STR), (5) the long-term repeatability (LTR, in two different ways), (6) the temperature dependence, (7) the water vapor sensitivity, (8) the linearity, and defined a calibration strategy. The reader is referred to Lebegue et al [20] for a detailed description of each test and to the series of figures provided in the supplementary material, the legends of which contain other technical details (S3-S11 Figs). The QCL's measurement frequency is 1 Hz.…”

Testing and evaluation of a new airborne system for continuous N<sub>2</sub>O, CO<sub>2</sub>, CO, and H<sub>2</sub>O measurements: the Frequent Calibration High-performance Airborne Observation System (FCHAOS)

“…A diverse range of approaches have been utilized in attempts to measure N 2 O emissions (Denmead, 2008;Rapson and Dacres, 2014). Flux chambers can quantify emissions from areas on the order of square meters (Bouwman et al, 2002;Marinho et al, 2004;Turner et al, 2008;Chadwick et al, 2014). Given the heterogeneity in N 2 O emission processes, extrapolation of limited flux chambers to accurately represent domains on the orders of 10-100 km 2 remains challenging (Pennock et al, 2005;Flechard et al, 2007).…”

Recent advances in measurement techniques for atmospheric carbon monoxide and nitrous oxide observations

“…Recent years brought the rapid development of a variety of alternative CO measurement techniques, and a variety of methods are now in use at atmospheric monitoring sites. Common methods include GC techniques (Gros et al, 1999;Novelli, 1999;van der Laan et al, 2009), non-dispersive infrared absorption (NDIR) (Parrish et al, 1994;Nedelec et al, 2003), vacuum ultra-violet resonance fluorescence (VURF) (Gerbig et al, 1999), Fourier transform infrared (FTIR) absorption (Griffith et al, 2012;Hammer et al, 2013a), near-IR cavity ring-down spectroscopy (NIR-CRDS) Yver Kwok et al, 2015), and systems using quantum cascade lasers (QCLs) in the mid-infrared such as mid-IR CRDS, off-axis integrated cavity output spectroscopy (OA-ICOS) (Baer et al, 2002;Provencal et al, 2005), and quantum cascade tuneable infrared laser direct absorption spectroscopy (QC-TILDAS) (McManus et al, 2015).…”