Performance of an open-path near-infrared measurement system for measurements of CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; and CH&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt; during extended field trials

Deutscher, Nicholas M.; Naylor, Travis A; Caldow, Christopher; McDougall, Hamish L.; Carter, Alex G.; Griffith, David

doi:10.5194/amt-14-3119-2021

Cited by 3 publications

(3 citation statements)

References 30 publications

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“…fractions are comparable to those achieved byGriffith et al (2018) (1.7 ppm for xCO 2 and 23 ppb for xCH 4 ), while they are substantially less precise thanDeutscher et al (2021) (0.28 ppm for xCO 2 and 2.1 ppb for xCH 4 ; in 3 min measurements) Deutscher et al (2021). mostly achieved this by a fixed connection of FTS instrument and telescope, replacing the fiber coupling…”

mentioning

confidence: 57%

“…Their system was built around an IRCube FTS manufactured by Bruker Opticsa compact, robust spectrometer. Since then, their setup was improved and developed into a portable version, suitable for field deployments (Deutscher et al, 2021). We followed a complementary path and built a new open-path system in Heidelberg with the goal of designing a permanent atmospheric observatory suitable for future methodological explorations and for long-term measurements of CO 2 and CH 4 above Heidelberg.…”

Section: Introductionmentioning

confidence: 99%

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An open-path observatory for greenhouse gases based on near-infrared Fourier transform spectroscopy

Schmitt,

Kuhn,

Kleinschek

et al. 2023

Preprint

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Abstract. Monitoring the atmospheric concentrations of the greenhouse gases (GHG) carbon dioxide CO2 and methane CH4 is a key ingredient for fostering our understanding of the mechanisms behind the sources and sinks of these gases and for verifying and quantitatively attributing their anthropogenic emissions. Here, we present the instrumental setup and performance evaluation of an open-path GHG observatory in the city of Heidelberg, Germany. The observatory measures path-averaged concentrations of CO2 and CH4 along a 1.55 km path in the urban boundary layer above the city. We are combining these open-path data with local in-situ measurements to evaluate the representativeness of these observation types on the kilometer-scale. This representativeness is necessary to accurately quantify emissions, since atmospheric models tasked with this job typically operate on kilometer-scale horizontal grids. For the operational period between Feb. 8 and Jul. 11, 2023, we find a precision of 2.7 ppm (0.58 %) and 18 ppb (0.89 %) for the dry air mole fractions of CO2 (xCO2) and CH4 (xCH4) in 5-minute measurements, respectively. After calibration, the open-path measurements show excellent agreement with the local in-situ data under atmospheric background conditions. Both datasets show clear signals of traffic CO2 emissions on the diurnal CO2 cycle. However, there are particular situations, such as under south-easterly wind conditions, where the in-situ and open-path data reveal distinct differences up to 20 ppm in xCO2 most likely related to their different sensitivity to local emission and transport patterns. Our setup is based on a Bruker IFS 125 HR Fourier transform spectrometer, which offers a spacious and modular design providing ample opportunities for future refinements of the technique with respect to finer spectral resolution and wider spectral coverage to inform on gases such as carbon monoxide and nitrogen dioxide.

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mentioning

confidence: 57%

Section: Introductionmentioning

confidence: 99%

An open-path observatory for greenhouse gases based on near-infrared Fourier transform spectroscopy

Schmitt,

Kuhn,

Kleinschek

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…Open-path measurements determine path-averaged concentrations and are less sensitive to immediate local sources compared to point measurements. Due to these characteristics, OP-FTIR has been used to monitor CO, CH 4 , CO 2 and nitrous oxide (N 2 O) from traffic emissions and other urban and rural sources [53][54][55][56][57]. The goal of this study is to quantify the changes in mole fractions and enhancements of CO, CO 2 , and CH 4 in downtown Toronto during the COVID-19 stay-at-home periods in 2020 and 2021, and to determine whether this system could detect the impact of changes in urban traffic emissions on CO and CO 2 .…”

Section: Introductionmentioning

confidence: 99%

Quantifying the Impact of the COVID-19 Pandemic Restrictions on CO, CO2, and CH4 in Downtown Toronto Using Open-Path Fourier Transform Spectroscopy

et al. 2021

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During the global COVID-19 pandemic, anthropogenic emissions of air pollutants and greenhouse gases (GHGs), especially traffic emissions in urban areas, have declined. Long-term measurements of trace gas concentrations in urban areas can be used to quantify the impact of emission reductions on GHG mole fractions. Open-path Fourier transform infrared (OP-FTIR) spectroscopy is a non-intrusive technique that can be used to simultaneously measure multiple atmospheric trace gases in the boundary layer. This study investigates the reduction of mole fractions and mole fraction enhancements above background for surface CO, CO2, and CH4 in downtown Toronto, Canada (the fourth largest city in North America) during the 2020 and 2021 COVID-19 stay-at-home periods. Mean values obtained from these periods were compared with mean values from a reference period prior to the 2020 restrictions. Mean CO mole fraction enhancement declined by 51 ± 23% and 42 ± 24% during the 2020 and 2021 stay-at-home periods, respectively. The mean afternoon CO2 mole fraction enhancement declined by 3.9 ± 2.6 ppm (36 ± 24%) and 3.5 ± 2.8 ppm (33 ± 26%) during the stay-at-home periods in 2020 and 2021. In contrast, CH4 mole fraction enhancement did not show any significant decrease. Diurnal variation in CO during the stay-at-home period in 2020 was also significantly reduced relative to the reference period in 2020. These reductions in trace gas mole fraction enhancements coincide with the decline of local traffic during the stay-at-home periods, with an estimated reduction in CO and CO2 enhancements of 0.74 ± 0.15 ppb and 0.18 ± 0.05 ppm per percentage decrease in traffic, respectively.

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An open-path observatory for greenhouse gases based on near-infrared Fourier transform spectroscopy

Schmitt,

Kuhn,

Kleinschek

et al. 2023

Atmos. Meas. Tech.

View full text Add to dashboard Cite

Abstract. Monitoring the atmospheric concentrations of the greenhouse gases (GHG) carbon dioxide (CO2) and methane (CH4) is a key ingredient for fostering our understanding of the mechanisms behind the sources and sinks of these gases and for verifying and quantitatively attributing their anthropogenic emissions. Here, we present the instrumental setup and performance evaluation of an open-path GHG observatory in the city of Heidelberg, Germany. The observatory measures path-averaged concentrations of CO2 and CH4 along a 1.55 km path in the urban boundary layer above the city. We combine these open-path data with local in situ measurements to evaluate the representativeness of these observation types on the kilometer scale. This representativeness is necessary to accurately quantify emissions, since atmospheric models tasked with this job typically operate on kilometer-scale horizontal grids. For the operational period between 8 February and 11 July 2023, we find a precision of 2.7 ppm (0.58 %) and 18 ppb (0.89 %) for the dry-air mole fractions of CO2 (xCO2) and CH4 (xCH4) in 5 min measurements, respectively. After bias correction, the open-path measurements show excellent agreement with the local in situ data under atmospheric background conditions. Both datasets show clear signals of traffic CO2 emissions in the diurnal xCO2 cycle. However, there are particular situations, such as under southeasterly wind conditions, in which the in situ and open-path data reveal distinct differences up to 20 ppm in xCO2, most likely related to their different sensitivity to local emission and transport patterns. Our setup is based on a Bruker IFS 125HR Fourier transform spectrometer, which offers a spacious and modular design providing ample opportunities for future refinements of the technique with respect to finer spectral resolution and wider spectral coverage to provide information on gases such as carbon monoxide and nitrogen dioxide.

show abstract

Performance of an open-path near-infrared measurement system for measurements of CO<sub>2</sub> and CH<sub>4</sub> during extended field trials

Cited by 3 publications

References 30 publications

An open-path observatory for greenhouse gases based on near-infrared Fourier transform spectroscopy

An open-path observatory for greenhouse gases based on near-infrared Fourier transform spectroscopy

Quantifying the Impact of the COVID-19 Pandemic Restrictions on CO, CO2, and CH4 in Downtown Toronto Using Open-Path Fourier Transform Spectroscopy

An open-path observatory for greenhouse gases based on near-infrared Fourier transform spectroscopy

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