A room temperature CO2 line list with ab initio computed intensities

Żak, Emil J.; Tennyson, Jonathan; Polyansky, Oleg L.; Lodi, Lorenzo; Zobov, Nikolay F.; Tashkun, S.A.; Perevalov, V.I.

doi:10.1016/j.jqsrt.2015.12.022

Cited by 97 publications

(140 citation statements)

References 58 publications

(81 reference statements)

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“…Although TCCON is not a solely HITRAN-based analysis (Wunch et al, 2011), a correction factor of 0.9898 for CO 2 , 0.9765 for CH 4 , and 1.0183 for H 2 O (Wunch et al, 2010) is needed to bring the overall TCCON retrievals into agreement with the WMO-based data. Additionally, theoretical calculations by (Zak et al, 2016) found an approximately 0.5% difference between CO 2 line parameters from HITRAN 2012 and their density functional theory calculations and an additional 0.5% difference between the calculations and new measurements by (Devi et al, 2016) in the 1.6-micron region. Certainly this discrepancy between retrievals from HITRAN and WMO-calibrated instruments is not fundamental and further experimental work should lead to improved spectral database parameters and much better agreement.…”

Section: Intercomparison Results and Discussionmentioning

confidence: 94%

Intercomparison of Open-Path Trace Gas Measurements with Two Dual Frequency Comb Spectrometers

Waxman¹,

Cossel²,

Truong³

et al. 2017

Preprint

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We present the first quantitative intercomparison between two open-path dual comb spectroscopy (DCS) instruments which were operated across adjacent 2-km open-air paths over a two-week period. We used DCS to measure the atmospheric absorption spectrum in the near infrared from 6021 to 6388 cm−1 (1565 to 1661 nm), corresponding to a 367 cm−1 bandwidth, at 0.0067 cm−1 sample spacing. The measured absorption spectra agree with each other to within 5×10−4 without any external calibration of either instrument. The absorption spectra are fit to retrieve concentrations for carbon dioxide (CO2), methane (CH4), water (H2O), and deuterated water (HDO). The retrieved dry mole fractions agree to 0.14% (0.57 ppm) for CO2, 0.35% (7 ppb) for CH4, and 0.40% (36 ppm) for H2O over the two-week measurement campaign, which included 23 °C outdoor temperature variations and periods of strong atmospheric turbulence. This agreement is at least an order of magnitude better than conventional active-source open-path instrument intercomparisons and is particularly relevant to future regional flux measurements as it allows accurate comparisons of open-path DCS data across locations and time. We additionally compare the open-path DCS retrievals to a WMO-calibrated cavity ringdown point sensor located along the path with good agreement. Short-term and long-term differences between the two systems are attributed, respectively, to spatial sampling discrepancies and to inaccuracies in the current spectral database used to fit the DCS data. Finally, the two-week measurement campaign yields diurnal cycles of CO2 and CH4 that are consistent with the presence of local sources of CO2 and absence of local sources of CH4.

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Section: Intercomparison Results and Discussionmentioning

confidence: 94%

Intercomparison of Open-Path Trace Gas Measurements with Two Dual Frequency Comb Spectrometers

Waxman¹,

Cossel²,

Truong³

et al. 2017

Preprint

View full text Add to dashboard Cite

show abstract

“…It would appear that this dependence is induced from the work of Coudert et al, as it is not observed in any other of the comparisons below which include the same bands. Such behavior has previously been shown to be the consequence of using effective Hamiltonians to represent intensities [60]. Figure 3a compares 4993 transitions provided in the study of Birk et al [7], which contains measurements from several experiments in the regions of 1250 -1750 cm −1 [34], 1850 -2280 cm −1 [6], 2390 -4000 cm −1 [6] and 4190 -4340 cm −1 [35].…”

Section: H 2 16 Omentioning

confidence: 91%

Calculated line lists for H216O and H218O with extensive comparisons to theoretical and experimental sources including the HITRAN2016 database

Conway

Gordon

Kyuberis

et al. 2020

Journal of Quantitative Spectroscopy and Radiative Transfer

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New line lists are presented for the two most abundant water isotopologues; H 2 16 O and H 2 18 O. The H 2 16 O line list extends to 25710 cm −1 with intensity stabilities provided via ratios of calculated intensities obtained from two different semi-empirical potential energy surfaces. The line list for H 2 18 O extends to 20000 cm −1 . The minimum intensity considered for all is 10 −30 cm molecule −1 at 296 K, assuming 100% abundance for each isotopologue. Fluctuation of calculated intensities caused by changes in the underlying potential energy are found to be significant, particularly for weak transitions. Direct comparisons are made against eighteen different sources of line intensities, both experimental and theoretical, many of which are used within the HITRAN2016 database. With some exceptions, there is excellent agreement between our line lists and the experimental intensities in HITRAN2016. In the infrared region, many H 2 16 O bands which exhibit intensity differences of 5-10% between to the most recent 'POKAZATEL' line list (Polyansky et al., [Mon. Not. Roy. Astron. Soc. 480, 2597] and observation, are now generally predicted to within 1%. For H 2 18 O, there are systematic differences in the strongest intensities calculated in this work versus those obtained from semi-empirical calculations. In the visible, computed cross sections show smaller residuals between our work and both HITRAN2016 and HITEMP2010 than POKAZATEL. While our line list accurately reproduces HITEMP2010 cross sections in the observed region, residuals produced from this comparison do however highlight the need to update line positions in the visible spectrum of HITEMP2010. These line lists will be used to update many transition intensities and line positions in the HITRAN2016 database.

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“…Although TCCON is not a solely HITRAN-based analysis , a correction factor of 0.9898 for CO 2 , 0.9765 for CH 4 , and 1.0183 for H 2 O (Wunch et al, 2010) is needed to bring the overall TCCON retrievals into agreement with the WMO-based data. Additionally, theoretical calculations by Zak et al (2016) found an approximately 0.5 % difference between CO 2 line parameters from HITRAN 2012 and their density functional theory calculations and an additional 0.5 % difference between the calculations and new measurements by Devi et al (2016) in the 1.6 µm region. Certainly this discrepancy between retrievals from HITRAN- and WMO-calibrated instruments is not fundamental, and further experimental work should lead to improved spectral database parameters and much better agreement.…”

Section: Comparison Of Open-path Dcs To a Crdsmentioning

confidence: 93%

Intercomparison of open-path trace gas measurements with two dual-frequency-comb spectrometers

et al. 2017

View full text Add to dashboard Cite

Abstract. We present the first quantitative intercomparison between two open-path dual-comb spectroscopy (DCS) instruments which were operated across adjacent 2 km openair paths over a 2-week period. We used DCS to measure the atmospheric absorption spectrum in the near infrared from 6023 to 6376 cm −1 (1568 to 1660 nm), corresponding to a 355 cm −1 bandwidth, at 0.0067 cm −1 sample spacing. The measured absorption spectra agree with each other to within 5 × 10 −4 in absorbance without any external calibration of either instrument. The absorption spectra are fit to retrieve path-integrated concentrations for carbon dioxide (CO 2 ), methane (CH 4 ), water (H 2 O), and deuterated water (HDO). The retrieved dry mole fractions agree to 0.14 % (0.57 ppm) for CO 2 , 0.35 % (7 ppb) for CH 4 , and 0.40 % (36 ppm) for H 2 O at ∼ 30 s integration time over the 2-week measurement campaign, which included 24 • C outdoor temperature variations and periods of strong atmospheric turbulence. This agreement is at least an order of magnitude better than conventional active-source open-path instrument intercomparisons and is particularly relevant to future regional flux measurements as it allows accurate comparisons of open-path DCS data across locations and time. We additionally compare the open-path DCS retrievals to a World Meteorological Organization (WMO)-calibrated cavity ring-down point sensor located along the path with good agreement. Shortterm and long-term differences between the open-path DCS and point sensor are attributed, respectively, to spatial sampling discrepancies and to inaccuracies in the current spectral database used to fit the DCS data. Finally, the 2-week measurement campaign yields diurnal cycles of CO 2 and CH 4 that are consistent with the presence of local sources of CO 2 and absence of local sources of CH 4 .

show abstract

A room temperature CO2 line list with ab initio computed intensities

Cited by 97 publications

References 58 publications

Intercomparison of Open-Path Trace Gas Measurements with Two Dual Frequency Comb Spectrometers

Intercomparison of Open-Path Trace Gas Measurements with Two Dual Frequency Comb Spectrometers

Calculated line lists for H216O and H218O with extensive comparisons to theoretical and experimental sources including the HITRAN2016 database

Intercomparison of open-path trace gas measurements with two dual-frequency-comb spectrometers

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