the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 22 Sep 2022
Evaluation of open and closed path sampling systems for determination of emission rates of NH3 and CH4 with inverse dispersion modelling
Yolanda Maria Lemes
Christoph Häni
Jesper Nørlem Kamp
Anders Feilberg
Abstract. The gas emission rates of ammonia (NH3) and methane (CH4) from an artificial source covering a surface area of 254 m2 were determined by inverse dispersion modelling (IDM) from point and line-integrated concentration measurements with closed and open-path analyzers. Eight controlled release experiments were conducted with different release rates ranging from 3.8 ± 0.21 to 17.4 ± 0.4 mg s-1 and from 30.7 ± 1.4 to 142.8 ± 2.9 mg s-1 for NH3 and CH4, respectively. The distance between the source and concentration measurement positions ranged from 15 m to 60 m. Our study consisted of more than 200 fluxes averaged intervals of 10 min or 15 min. The different releases cover a range of different climate conditions: cold (< 5 °C), temperate (< 13 °C) and warm (< 18 °C). As the average of all releases with all instrument types, the CH4 recovery rate QbLS/Q was 0.95 ± 0.08 (n = 19). There was much more variation in the recovery of NH3, with an average of 0.66 ± 0.15 (n = 10) for all the releases with the line-integrated system. However, with an improved sampling line placed close to the source an average recovery rate of 0.82 ± 0.05 (n = 3) was obtained for NH3. Under comparable conditions, the recovery rate obtained with an open-path analyzer was 0.91 ± 0.07 (n = 3). The effects of measurement distance, physical properties of the sampling line, and deposition are discussed.
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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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Supplement
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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
(1558 KB) -
Supplement
(2874 KB) - BibTeX
- EndNote
- Final revised paper
Journal article(s) based on this preprint
Yolanda Maria Lemes et al.
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2022-867', Joseph Pitt, 24 Oct 2022
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2022/egusphere-2022-867/egusphere-2022-867-RC1-supplement.pdf
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AC1: 'AC1', Yolanda Maria Lemes Perschke, 06 Jan 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2022/egusphere-2022-867/egusphere-2022-867-AC1-supplement.pdf
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AC1: 'AC1', Yolanda Maria Lemes Perschke, 06 Jan 2023
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RC2: 'Comment on egusphere-2022-867', Anonymous Referee #2, 19 Nov 2022
Lemes et al. evaluated the performance of the inverse dispersion modeling with controlled releases of NH3 and CH4 based on both open and closed path atmospheric sampling. The work used one single model, the backward Lagrangian stochastic model, to perform the analysis. Since the deposition of NH3 on the surface may be significant and that of CH4 not, the simultaneous measurements could provide a means of evaluating the deposition rates of NH3. To this end, this work can be potentially quite interesting to the community. On the other hand, the manuscript can be better structured, and several important aspects should be clarified before the manuscript can be accepted for publication.
General comments:
- Here the recovery rates were used to calculate the deposition velocity of NH3. Although the authors are aware that this is not completely correct, and call it “apparent” deposition velocity, the assumptions behind this calculation have not been fully discussed, e.g., what are the sampling biases, the inverse modeling biases, the measurement biases that are related to and not related to sampling line deposition?
- The different causes for the mismatches in the calculated deposition rates have been presented; however, not sufficient efforts have been attempted to disentangle them. For example, the deposition of NH3 on the sampling line could be directly compared, evaluated, and corrected for. Why has this not been done?
- A thorough analysis (or some sort of analysis) of the uncertainties of the inverse dispersion modeling is lacking. Note that inverse dispersion modeling has already been applied and evaluated in many other studies, e.g., Weller et al., 2018, Caulton et al., 2018, Shah et al., 2020, Andersen et al., 2021, Morales et al., 2022. It is well known that the inverse dispersion estimate based on one single measurement path is very uncertainty, which must be at least acknowledged.
Minor comments:
P48: labor intensive and costly
P97: are adequately met
L106-109: It is not really novel
P129: …analyzers from Picarro
P133: measures
Table 1: What’s the uncertainty of the content of NH3 of the gas cylinder? The 2% uncertainty for both NH3 and N2?
L176-178: It’s confusing here. What’s the difference of a single point vs. the rest of the experiments? As is written, they all use PTFE tubes, insulated, and heated, and 40â. Is 80â the only difference?
L213: calculated
L258: leaf area index
L306-312: This paragraph belongs to the method section.
L385: These results
L406: Any correlation analysis result here?
Citation: https://doi.org/10.5194/egusphere-2022-867-RC2 -
AC2: 'AC2', Yolanda Maria Lemes Perschke, 06 Jan 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2022/egusphere-2022-867/egusphere-2022-867-AC2-supplement.pdf
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2022-867', Joseph Pitt, 24 Oct 2022
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2022/egusphere-2022-867/egusphere-2022-867-RC1-supplement.pdf
-
AC1: 'AC1', Yolanda Maria Lemes Perschke, 06 Jan 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2022/egusphere-2022-867/egusphere-2022-867-AC1-supplement.pdf
-
AC1: 'AC1', Yolanda Maria Lemes Perschke, 06 Jan 2023
-
RC2: 'Comment on egusphere-2022-867', Anonymous Referee #2, 19 Nov 2022
Lemes et al. evaluated the performance of the inverse dispersion modeling with controlled releases of NH3 and CH4 based on both open and closed path atmospheric sampling. The work used one single model, the backward Lagrangian stochastic model, to perform the analysis. Since the deposition of NH3 on the surface may be significant and that of CH4 not, the simultaneous measurements could provide a means of evaluating the deposition rates of NH3. To this end, this work can be potentially quite interesting to the community. On the other hand, the manuscript can be better structured, and several important aspects should be clarified before the manuscript can be accepted for publication.
General comments:
- Here the recovery rates were used to calculate the deposition velocity of NH3. Although the authors are aware that this is not completely correct, and call it “apparent” deposition velocity, the assumptions behind this calculation have not been fully discussed, e.g., what are the sampling biases, the inverse modeling biases, the measurement biases that are related to and not related to sampling line deposition?
- The different causes for the mismatches in the calculated deposition rates have been presented; however, not sufficient efforts have been attempted to disentangle them. For example, the deposition of NH3 on the sampling line could be directly compared, evaluated, and corrected for. Why has this not been done?
- A thorough analysis (or some sort of analysis) of the uncertainties of the inverse dispersion modeling is lacking. Note that inverse dispersion modeling has already been applied and evaluated in many other studies, e.g., Weller et al., 2018, Caulton et al., 2018, Shah et al., 2020, Andersen et al., 2021, Morales et al., 2022. It is well known that the inverse dispersion estimate based on one single measurement path is very uncertainty, which must be at least acknowledged.
Minor comments:
P48: labor intensive and costly
P97: are adequately met
L106-109: It is not really novel
P129: …analyzers from Picarro
P133: measures
Table 1: What’s the uncertainty of the content of NH3 of the gas cylinder? The 2% uncertainty for both NH3 and N2?
L176-178: It’s confusing here. What’s the difference of a single point vs. the rest of the experiments? As is written, they all use PTFE tubes, insulated, and heated, and 40â. Is 80â the only difference?
L213: calculated
L258: leaf area index
L306-312: This paragraph belongs to the method section.
L385: These results
L406: Any correlation analysis result here?
Citation: https://doi.org/10.5194/egusphere-2022-867-RC2 -
AC2: 'AC2', Yolanda Maria Lemes Perschke, 06 Jan 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2022/egusphere-2022-867/egusphere-2022-867-AC2-supplement.pdf
Peer review completion
Journal article(s) based on this preprint
Yolanda Maria Lemes et al.
Yolanda Maria Lemes 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
(1558 KB) - Metadata XML
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Supplement
(2874 KB) - BibTeX
- EndNote
- Final revised paper