Monitoring Urban Greenhouse Gases Using Open-Path Fourier Transform Spectroscopy

Byrne, Brendan; Strong, Kimberly; Colebatch, Orfeo; You, Yuan; Wunch, Debra; Ars, Sébastien; Jones, Dylan B. A.; Fogal, P. F.; Mittermeier, R. L.; Worthy, Doug; Griffith, David

doi:10.1080/07055900.2019.1698407

Cited by 12 publications

(11 citation statements)

References 43 publications

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“…To do this, two shutterlowered spectra taken before and after each shutter-raised spectrum are first averaged, and then subtracted from the corresponding shutter-raised spectrum to calculate the absorption spectrum. The subtraction is similar to what is used in Byrne et al [58], and is performed using the routine developed by Geddes et al [59]. The transmission spectrum is then calculated by taking the ratio of this calculated absorption spectrum to a previously determined background spectrum, as described in Section 2.2.…”

Section: Data Processing and Gas Retrievalsmentioning

confidence: 99%

“…There was no weather station beside the retro-reflector before November 2018, so for this period the input temperature was taken as the temperature measured on the roof of MP plus 0.45 K, considering the average temperature difference between the measurements on the roof of MP and beside the retro-reflector, and scaling to the midpoint of the open path. In this study, CO, CO 2 and N 2 O mole fractions with respect to whole air are retrieved in the range 2141-2235 cm −1 (H 2 O is interfering gas) and CH 4 is retrieved in the range 2900-3027 cm −1 (H 2 O is interfering gas) as summarized in Table 1 [56,58]. H 2 O mole fraction is retrieved in the range 2713-2952 cm −1 [58] and used to calculate dry-air mole fractions of gases by…”

Section: Data Processing and Gas Retrievalsmentioning

confidence: 99%

“…In this study, CO, CO 2 and N 2 O mole fractions with respect to whole air are retrieved in the range 2141-2235 cm −1 (H 2 O is interfering gas) and CH 4 is retrieved in the range 2900-3027 cm −1 (H 2 O is interfering gas) as summarized in Table 1 [56,58]. H 2 O mole fraction is retrieved in the range 2713-2952 cm −1 [58] and used to calculate dry-air mole fractions of gases by…”

Section: Data Processing and Gas Retrievalsmentioning

confidence: 99%

“…The mean daily afternoon CH 4 and ∆CH 4 during the two stay-at-home periods (2020 Period 2 and 2021 Period 3) are statistically the same. The mean afternoon CH 4 and ∆CH 4 varied between examined periods and the variability in CH 4 between periods and years is likely influenced by local sources such as the steam plant immediately to the southwest of the site [58] and several buildings to the south of the site that use natural gas for physical plant infrastructure such as hot water boilers. CH 4 and ∆CH 4 showed elevation in southwest and southeast sectors (Figure 4c,f) in Period 1 in 2018.…”

Section: Daily Mole Fractions and Enhancements Above Backgroundmentioning

confidence: 99%

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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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Section: Data Processing and Gas Retrievalsmentioning

confidence: 99%

Section: Data Processing and Gas Retrievalsmentioning

confidence: 99%

Section: Data Processing and Gas Retrievalsmentioning

confidence: 99%

Section: Daily Mole Fractions and Enhancements Above Backgroundmentioning

confidence: 99%

See 2 more Smart Citations

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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“…CO 2 emissions estimated this way at the urban scale have been shown to have an uncertainty of 50%–200% (Asefi‐Najafabady et al., 2014; J. C. Turnbull et al., 2011). The bottom‐up approach also fails to accurately determine the contribution of urban CO 2 capture by green infrastructures, which are currently being promoted as a means to reduce the carbon footprint (Byrne et al., 2020). Some of the limitations include uncertainty in the time scales for respiration (RESP) of carbon previously taken up through photosynthesis and the effect of urban climate and topography on the urban biosphere.…”

Section: Introductionmentioning

confidence: 99%

Exploring the Potential of Using Carbonyl Sulfide to Track the Urban Biosphere Signal

Villalba

Whelan

Montzka³

et al. 2021

JGR Atmospheres

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Quantifying the impact of the COVID-19 lockdown on air quality in downtown Toronto using open-path Fourier transform spectroscopy

You

Byrne

Colebatch

et al. 2021

Preprint

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During the global COVID-19 pandemic, anthropogenic emissions of air pollutants and greenhouse gases, especially traffic emissions in urban areas, have declined significantly. Long-term measurements of trace gas concentrations in urban areas can be used to quantify the impact of emission reductions on local air quality. 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 surface CO, CO2 , and CH4 mole fractions during the lockdown in downtown Toronto, Canada, which is the fourth largest city in North America. The mean daily CO mole fraction anomaly (ΔCO) for the period from March 14 to May 18, 2020 declined by 46 ± 16% compared to the period before lockdown from January 13 to March 13, 2020. The mean daily ΔCO during the lockdown also declined relative to the same period in previous years: by 50 ± 20% relative to 2019 and by 44 ± 25% relative to 2018. Changes in the diurnal variations of CO, CO2 and CH4 during the lockdown are also investigated and compared to 2019 and 2018. Both CO and CO2 show early morning maxima on weekdays corresponding to rush hour. The change of the amplitude of the diurnal variation in CO during the lockdown is significant, compared to the period before lockdown. The differences in the diurnal variation in CO during the same two periods in 2019 and 2018 are not significant. Ratios of CO/CO2 anomalies show seasonal variations, which are also likely due to seasonal changes of emissions from local sources. These results show that the COVID-19 lockdown in Toronto modified surface mole fractions, diurnal variations, and ratios of air pollutants monitored by OP-FTIR. In addition, measured CO mole fractions are compared with simulated CO mole fractions by WRF-STILT to assess the relationship between atmospheric measurements and urban emissions from Toronto.

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Monitoring Urban Greenhouse Gases Using Open-Path Fourier Transform Spectroscopy

Cited by 12 publications

References 43 publications

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

Exploring the Potential of Using Carbonyl Sulfide to Track the Urban Biosphere Signal

Quantifying the impact of the COVID-19 lockdown on air quality in downtown Toronto using open-path Fourier transform spectroscopy

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