the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Open-path measurement of stable water isotopologues using mid-infrared dual-comb spectroscopy
Daniel I. Herman
Griffin Mead
Fabrizio R. Giorgetta
Esther Baumann
Nathan Malarich
Brian R. Washburn
Nathan R. Newbury
Ian Coddington
Abstract. We present an open-path mid-infrared dual-comb spectrometer (DCS) capable of precise measurement of the stable water isotopologues H216O and HD16O. This system ran in a remote configuration at a rural test site for 3.75 months with 60 % uptime and achieved a precision of <2 ‰ on the normalized ratio of H216O and HD16O (δD) in 1000 seconds. Here, we compare the δD values from the DCS to those from the National Ecological Observatory Network (NEON) isotopologue point sensor network. Over the multi-month campaign, the mean difference between the DCS δD values and the NEON δD values from a similar ecosystem is <2 ‰ with a standard deviation of 18 ‰, which demonstrates the inherent accuracy of DCS measurements over a variety of atmospheric conditions. We observe time-varying diurnal profiles and seasonal trends that are mostly correlated between the sites on daily time scales. This observation motivates the development of denser ecological monitoring networks aimed at understanding regional and synoptic scale water transport. Precise and accurate open-path measurements using DCS provide new capabilities for such networks.
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Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Preprint
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
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Journal article(s) based on this preprint
Daniel I. Herman et al.
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2022-1263', Anonymous Referee #2, 16 Feb 2023
This paper describes a novel technique for open path measurement of water vapor isotopologues and makes some preliminary analysis of measurements acquired during a 3 month period in the Denver, Colorado area. The measurements are compared to point measurements acquired 70 km away and show both similarities and differences that can be interpreted.
The paper is extrmely clear, the figures are of high quality, and all discussions make sense. The abstract is a fair summary of what has been achieved in the study.
This paper should be accepted as is.
Citation: https://doi.org/10.5194/egusphere-2022-1263-RC1 -
AC1: 'Reply on RC2', Kevin Cossel, 06 Apr 2023
We thank the reviewers for their time and for the kind remarks.
We agree with reviewer 2 that the discrepancies between HITRAN and VSMOW are indeed negligible for this work and appreciate the careful checking of the math. The 1 permil number given was intended to be an upper limit depending on the exact isotope ratio used (for example, the numbers in Griffith 2018 differ slightly from that IUPAC technical report), but it was also indeed too large. Instead, we have changed that sentence to read: "Finally, we note that there are slight differences between isotopologue ratios determined using HITRAN and ratios in the VSMOW scale; however, these differences are negligible here (Griffith, 2018)."
We have also corrected Line 31 to say isotopologue ratio instead of isotope ratio.
Citation: https://doi.org/10.5194/egusphere-2022-1263-AC1
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AC1: 'Reply on RC2', Kevin Cossel, 06 Apr 2023
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RC2: 'Comment on egusphere-2022-1263', Ivan Prokhorov, 20 Feb 2023
Herman and his colleagues present a truly impressive accomplishment in measuring the water D/H ratio using DCS in an open path configuration. The methodology is explained in details and supported by preliminary field measurements. The obtained data is interpreted in a coinsice manner.
I would like to bring authors' attention to descripancies between isotopologue ratios reported in HITRAN and those in VSMOV material. Following IUPAC technical report https://doi.org/10.1351/pac200274101987, rD_VSMOW = 15574/99984426, it gives HDO/HHO = 3.115285e-04 in agreement with the value reported in Line 30. HITRAN2020 has HDO/HHO = 3.106930e-4/0.997317 = 3.115288e-04. The difference is <1e-3 permil, which is much less than 1 permil reported in Line 265. Hence, it is insignificant to be included in the interpretation of the results. Another minor remark to Line 31, R_VSMOW = 0.0003115 is the isotopologue ratio in VSMOW material, not the isotope ratio, please correct the text accordingly.
The paper is very well written, it is certainly within the scope of AMT, and deserves to be published.
Citation: https://doi.org/10.5194/egusphere-2022-1263-RC2 -
AC1: 'Reply on RC2', Kevin Cossel, 06 Apr 2023
We thank the reviewers for their time and for the kind remarks.
We agree with reviewer 2 that the discrepancies between HITRAN and VSMOW are indeed negligible for this work and appreciate the careful checking of the math. The 1 permil number given was intended to be an upper limit depending on the exact isotope ratio used (for example, the numbers in Griffith 2018 differ slightly from that IUPAC technical report), but it was also indeed too large. Instead, we have changed that sentence to read: "Finally, we note that there are slight differences between isotopologue ratios determined using HITRAN and ratios in the VSMOW scale; however, these differences are negligible here (Griffith, 2018)."
We have also corrected Line 31 to say isotopologue ratio instead of isotope ratio.
Citation: https://doi.org/10.5194/egusphere-2022-1263-AC1
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AC1: 'Reply on RC2', Kevin Cossel, 06 Apr 2023
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2022-1263', Anonymous Referee #2, 16 Feb 2023
This paper describes a novel technique for open path measurement of water vapor isotopologues and makes some preliminary analysis of measurements acquired during a 3 month period in the Denver, Colorado area. The measurements are compared to point measurements acquired 70 km away and show both similarities and differences that can be interpreted.
The paper is extrmely clear, the figures are of high quality, and all discussions make sense. The abstract is a fair summary of what has been achieved in the study.
This paper should be accepted as is.
Citation: https://doi.org/10.5194/egusphere-2022-1263-RC1 -
AC1: 'Reply on RC2', Kevin Cossel, 06 Apr 2023
We thank the reviewers for their time and for the kind remarks.
We agree with reviewer 2 that the discrepancies between HITRAN and VSMOW are indeed negligible for this work and appreciate the careful checking of the math. The 1 permil number given was intended to be an upper limit depending on the exact isotope ratio used (for example, the numbers in Griffith 2018 differ slightly from that IUPAC technical report), but it was also indeed too large. Instead, we have changed that sentence to read: "Finally, we note that there are slight differences between isotopologue ratios determined using HITRAN and ratios in the VSMOW scale; however, these differences are negligible here (Griffith, 2018)."
We have also corrected Line 31 to say isotopologue ratio instead of isotope ratio.
Citation: https://doi.org/10.5194/egusphere-2022-1263-AC1
-
AC1: 'Reply on RC2', Kevin Cossel, 06 Apr 2023
-
RC2: 'Comment on egusphere-2022-1263', Ivan Prokhorov, 20 Feb 2023
Herman and his colleagues present a truly impressive accomplishment in measuring the water D/H ratio using DCS in an open path configuration. The methodology is explained in details and supported by preliminary field measurements. The obtained data is interpreted in a coinsice manner.
I would like to bring authors' attention to descripancies between isotopologue ratios reported in HITRAN and those in VSMOV material. Following IUPAC technical report https://doi.org/10.1351/pac200274101987, rD_VSMOW = 15574/99984426, it gives HDO/HHO = 3.115285e-04 in agreement with the value reported in Line 30. HITRAN2020 has HDO/HHO = 3.106930e-4/0.997317 = 3.115288e-04. The difference is <1e-3 permil, which is much less than 1 permil reported in Line 265. Hence, it is insignificant to be included in the interpretation of the results. Another minor remark to Line 31, R_VSMOW = 0.0003115 is the isotopologue ratio in VSMOW material, not the isotope ratio, please correct the text accordingly.
The paper is very well written, it is certainly within the scope of AMT, and deserves to be published.
Citation: https://doi.org/10.5194/egusphere-2022-1263-RC2 -
AC1: 'Reply on RC2', Kevin Cossel, 06 Apr 2023
We thank the reviewers for their time and for the kind remarks.
We agree with reviewer 2 that the discrepancies between HITRAN and VSMOW are indeed negligible for this work and appreciate the careful checking of the math. The 1 permil number given was intended to be an upper limit depending on the exact isotope ratio used (for example, the numbers in Griffith 2018 differ slightly from that IUPAC technical report), but it was also indeed too large. Instead, we have changed that sentence to read: "Finally, we note that there are slight differences between isotopologue ratios determined using HITRAN and ratios in the VSMOW scale; however, these differences are negligible here (Griffith, 2018)."
We have also corrected Line 31 to say isotopologue ratio instead of isotope ratio.
Citation: https://doi.org/10.5194/egusphere-2022-1263-AC1
-
AC1: 'Reply on RC2', Kevin Cossel, 06 Apr 2023
Peer review completion
Post-review adjustments
Journal article(s) based on this preprint
Daniel I. Herman et al.
Daniel I. Herman et al.
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
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