the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 14 Jul 2026
From research to reality: Academic methane measurement systems tested at the TADI controlled release facility
Abstract. Accurate methane emission quantification is critical for climate mitigation efforts in the oil and gas industry. This study evaluates the performance of five academic methane measurement systems through single-blind controlled release testing at the TotalEnergies Anomaly Detection Initiatives (TADI) facility in France during June and September 2024. Vehicle-based teams from Technical University of Denmark, Heidelberg University, and a collaborative team from Utrecht University/LSCE/Cyprus Institute/Royal Holloway deployed mobile in situ measurement systems, while aircraft-based solutions from Empa/UZH and FAAM BAe-146 utilized hyperspectral imaging and airborne in situ measurements, respectively. Vehicle-based systems demonstrated strong detection capabilities with true positive rates of 93–100 % and minimum detection thresholds below 1 kg CH₄ h⁻¹. Quantification accuracy varied significantly, with slopes ranging from 0.38 to 1.04 when comparing estimated versus true emission rates. Aircraft systems showed more variable performance due to operational constraints and limited data availability. Post-unblinding analysis revealed critical insights into systematic errors, including background concentration calculation issues and wind measurement limitations. Low wind conditions (<2 m s⁻¹) particularly challenged quantification accuracy across all platforms. These findings highlight the importance of robust validation procedures and high-quality meteorological data for reliable methane emission quantification in real-world applications.
Competing interests: At least one of the (co-)authors is a member of the editorial board of Atmospheric Measurement Techniques.
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.- Preprint
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Status: final response (author comments only)
- RC1: 'Comment on egusphere-2026-1744', Anonymous Referee #2, 03 Aug 2026
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RC2: 'Comment on egusphere-2026-1744', Anonymous Referee #3, 11 Sep 2026
General Comments
The authors report on a experiment evaluating the ability of various sensors and approaches for the detection of methane plumes and estimation of emission rates. A particular strength is an evaluation of the important role of wind speed on the ability to detect methane and accuracy of emissions rates as expressed by r2 and slope. The authors compared five approaches, three using mobile facilities and two using airborne sensors.
Specific to AMT
In terms of criteria specific by the journal, I would rate the paper as follows
1. Does the paper address relevant scientific questions within the scope of AMT?: Yes
2. Does the paper present novel concepts, ideas, tools, or data?: Some of the data, such as AVIRIS-4 is novel
3. Are substantial conclusions reached?:Yes.
4. Are the scientific methods and assumptions valid and clearly outlined?: No. More detail is required for many of the approaches.
5. Are the results sufficient to support the interpretations and conclusions?:No. The assessment of airborne systems is insufficient.
6. Is the description of experiments and calculations sufficiently complete and precise to allow their reproduction by fellow scientists (traceability of results)?: No. Details are lacking for a number of approaches tested.
7. Do the authors give proper credit to related work and clearly indicate their own new/original contribution?: No. The references are a major weakness
8. Does the title clearly reflect the contents of the paper?: No. The title should be revised (see below)
9. Does the abstract provide a concise and complete summary?: Yes. The abstract is sufficient
10) Is the overall presentation well structured and clear?: Yes.
11) Is the language fluent and precise?: Yes.
12) Are mathematical formulae, symbols, abbreviations, and units correctly defined and used?: Mixed. The paper is pretty short on equations and not every figure has unit defined.
13) Should any parts of the paper (text, formulae, figures, tables) be clarified, reduced, combined, or eliminated?: Yes. Figure 5 should be revised, and the airborne assessment is flawed by poor atmospheric conditions.
14) Are the number and quality of references appropriate?: No. The references are in need of improvement
15) Is the amount and quality of supplementary material appropriate?: Yes. The supplement is quite nice.
In terms of my own review, the paper appears similar to a number of double blind detection studies and is particularly important given the importance of methane. I particularly enjoyed the supplement and found some of the results (e.g. high accuracies using tracers and a mobile lab, importance of wind) good contributions to the literature. However, there are a number of other areas where the paper has significant weaknesses. These include
1) The title. I am not really sure what “From Research to Reality” means, nor why the focus is on “Academic methane measurements”. From Research to Operations might be a better description and I would remove the word “academic” whcih can be interpreted as pejorative.
2) The Introduction is in need of significant revisions. As it is written, a reader would not be aware of how much actual work has gone into airborne estimation, nor validation of those estimates. Few of what I would consider to be the definitive papers on the subject are cited, with the authors focusing on a fairly narrow selection of articles that include almost all of the airborne work, including some with controlled releases and field measures to validate estimates. A selection that should be considered include:
Controlled release and field validation
Thorpe et al., 2016, Mapping methane concentrations from a controlled release experiment using the next generation airborne visible/infrared imaging spectrometer (AVIRIS-NG), Remote Sensing of Environment, 179, pgs 104-115.
Given the subject matter, I do not understand why this paper was not cited.
Ayasse AK, Cusworth DH, Howell K, O'Neill K, Conrad BM, Johnson MR, Heckler J, Asner GP, Duren R. 2024, Probability of Detection and Multi-Sensor Persistence of Methane Emissions from Coincident Airborne and Satellite Observations. Environ Sci Technol. 2024 Dec 10;58(49):21536-21544.
Cusworth et al. 2024, Quantifying methane emissions from United States landfills. Science 383,1499-1504(2024).DOI:10.11
Methods for airborne retrievals
DOAS (most accurate)
Thorpe et al., 2017, Airborne DOAS retrievals of methane, carbon dioxide, and water vapor concentrations at high spatial resolution: application to AVIRIS-NG, Atmos. Meas. Tech., 10, 3833–3850
Cluster-tuned Matched Filters
Thorpe et al., 2013, High resolution mapping of methane emissions from marine and terrestrial sources using a Cluster-Tuned Matched Filter technique and imaging spectrometry,Remote Sensing of Environment, Volume 134,2013,Pages 305-318, ISSN 0034-4257,
Albedo corrected retrievals
Foote et al., 2021; ,Impact of scene-specific enhancement spectra on matched filter greenhouse gas retrievals from imaging spectroscopy, Remote Sensing of Environment, Volume 264,2021,
Real-time plume detection
Thompson et al., 2015, Real-time remote detection and measurement for airborne imaging spectroscopy: a case study with methane, Atmos. Meas. Tech., 8, 4383–4397, https://doi.org/10.5194/amt-8-4383-2015, 2015.
Sensitivity analysis
Ayasse et al., 2018, Evaluating the effects of surface properties on methane retrievals using a synthetic airborne visible/infrared imaging spectrometer next generation (AVIRIS-NG) image, Remote Sensing of Environment, Volume 215, 2018, Pages 386-397,
Review articles and high profile articles on airborne retrievals
Review article: Spaceborne retrievals
Jacob, D. J., Varon, D. J., Cusworth, D. H., Dennison, P. E., Frankenberg, C., Gautam, R., Guanter, L., Kelley, J., McKeever, J., Ott, L. E., Poulter, B., Qu, Z., Thorpe, A. K., Worden, J. R., and Duren, R. M.2022, Quantifying methane emissions from the global scale down to point sources using satellite observations of atmospheric methane, Atmos. Chem. Phys., 22, 9617–9646, https://doi.org/10.5194/acp-22-9617-2022
Sherwin, E.D., Rutherford, J.S., Zhang, Z. et al. 2024, US oil and gas system emissions from nearly one million aerial site measurements. Nature 627, 328–334. https://doi.org/10.1038/s41586-024-07117-5
Daniel H. Cusworth et al. 2024, Quantifying methane emissions from United States landfills.Science383,1499-1504(2024).DOI:10.11
There is also a wealth of spaceborne retrievals, although those might be a bit off topic. Finally, airborne methane retrievals date all the way back to 2010, although much of that work did not include accuracy assessment.
3) Some of the papers that are cited appear to have incomplete references, such as El Abbadi et al., which includes authors, a title, and date but not a publication venue. Wilson et al., 1976 also appears incomplete
4) A number of the figures are in need of improvement. This includes Figure 5 (the left frame is very difficult to read), Figure 9 (What are the units on the y axis, estimated release rate)
5) Many plumes are not really gaussian. This needs to be stated as a weakness. Given wind speed and direction that is often highly variable, the gaussian assumption is typically poor.
6) Experimental design. There are a number of issues regarding measurement conditions that complicate the results. These include
a) Cloud cover. Poor atmospheric conditions seriously hampered the ability of the authors to truly assess the performance of airborne systems, with one system having only one successful retrieval, and the other (AVIRIS-4) only small number. Given the highly successful campaigns described for California (Duren et al., 2019. California’s Super Emitters, Nature, the US, Sherwin et al, 2024, US oil and gas system emissions from nearly one million aerial site measurements, Nature, and landfills (with validation), Cusworth et al., 2024, Science, the assessments here are not sufficient to truly evaluate those systems.
b) In assessing the airborne results, more needs to be said about the surface composition of the area. For example, asphalt surfaces tend to be confusers even for matched filters, and the accuracy varies with surface albedo (See Ayasse et al., 2018).
c) The mobile results are very interesting, especially the one using the tracers. However, it needs to be pointed out that those systems need to be guided to a potential source, especially if a tracer has to be released at the potential source. A vast majority of the sources will not be found using that approach.
I understand these types of studies can be difficult, but the assessment of the airborne systems is flawed because of the environmental conditions during acquisition. This needs to be carefully considered in any discussion.
Specific Comments
Section 1: See above. The entire introduction is in need of significant revision to better reflect the state of the science for methane retrievals, especially using airborne and spaceborne systems.
Line 38: I would add a “the” to “the Technical…. “
Line 60. IPCC 2023 is missing from the references
Line 64. This statement needs a reference to support it,.
Line 71. Revise to read “making quantifying methane emissions accurately a critical”
Line 73. Commonplace should be followed with citations. See some of the references above.
Line 175. Table 2 is cited twice
Line 220. See comment on Gaussian plumes
Line 269. There is an error here.
Line 302. There is an excess “for” here. Revise to read “members were converging”
Line 354. Please use metric. Even in the US metric units are used in most scientific papers.
Line 358. Revise to read “it is acknowledged that”
Discussion. The discussion section needs to be revised to better acknowledge prior work on this subject (e.g. Thorpe et al., 2016) and better discuss issues with the design of the study, for example, which place significant constraints on airborne acquisitions due to clouds. Many large emissions sources are not as limited by clouds.
I did like Section 4.2.3. Background concentrations are a serious issue. For some regions, such as the Los Angeles Basin, they are remarkably high due to numerous seep sources. I also liked Section 4.2.2 (Although it is not clear why this section comes after 4.2.3). Wind is a very serious issue and virtually all of the airborne and spaceborne approaches are highly dependent on accurate estimates of wind speeds. Emission rates can only be retrieved if wind speed is accurately determined, and coarse spatial resolution data sets such as ERA5 are clearly insufficient.
Citation: https://doi.org/10.5194/egusphere-2026-1744-RC2
Data sets
amcmanemin2/TADI_controlled_release_2024: Commercial team publication Audrey McManemin https://doi.org/10.5281/zenodo.18381031
Model code and software
amcmanemin2/TADI_controlled_release_2024: Commercial team publication Audrey McManemin https://doi.org/10.5281/zenodo.18381031
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General Comments:
This paper details results from a 2024 controlled release campaign evaluating methane leak detection and quantification from five academic teams at the TADI controlled release site in Pau, France. A variety of teams conducted measurements of single-blind releases with sampling occurring on vehicle and aircraft platforms. Details of detection and quantification for all teams are provided, along with analysis detailing the effect of atmospheric conditions on the ability of each team to identify a release and provide accurate quantification. Overall, the results are well-presented and within the scope of AMT. Publication is recommended with the following minor revisions.
Specific Corrections:
One methodological point on quantification accuracies (i.e. regressions Figure 8 and related analysis) that could be considered: All participating teams provide uncertainty estimates along with quantified emission rates; however, all regressions between estimated and true emission rates use ordinary least squares. The authors could consider utilizing generalized least squares (i.e. uncertainty-weighted), which can explicitly account for the variable uncertainty on each data point when calculating regressions for quantification accuracies. The primary benefit of this method would be to reduce the effect of outliers with large uncertainties on regressions (which doesn’t seem to be driving quantification errors in this study), and better-use the uncertainty estimates provided for each quantification. As this study is a follow-on piece to McManemin 2026 which evaluated commercial methane detection and quantification technologies with similar methods during the same controlled release, it is acceptable if the authors wish to maintain consistency with this earlier paper.
75: “in situ sensors” are defined, but “active scanning systems” are left undefined. Do active scanning systems not also measure local concentrations? As all sensors in this paper are either vehicle based (in situ) or aircraft (remote imaging systems), I recommend defining active scanning systems or removing the discussion for this piece entirely.
281: RHUL’s method undefined. “a traditional determination process based on the cloud coverage and the wind speed at the time of measurements” Please provide a citation or more description of the methodology used.
Figure 3d is very hard to read, and missing labels or what the cells (Letters A-F?) indicate. Please improve readability of this figure.
341: Is the LGR precision at a given averaging time available? All other in situ sensors present a similar metric and would be helpful in comparing the different sensors used in this study.
436: The definition of “smaller releases” is ambiguous in this section. I believe that it refers to less than 100 kg/hr, but please clarify. Additionally, plots of POD are shown for less than 30kg/hr, but this section segments at 100kg/hr. Please provide a small justification for the different choices made in what constitutes a “smaller” release magnitude.
475: “Low wind speed conditions (below 1 m/s) are correlated with increased scatter and underestimation.” The reader can look to Figure 9 and observe differences in r^2 across wind speed bins, however these are segmented from 0-2 m/s and the text claims “below 1 m/s”. If the authors are attempting to comment on differences between the 2 m/s threshold and the displayed 0-2m/s binning, some additional statistics would be helpful to make this claim.
478 and later: Here and after the term “stable wind conditions” may be confusing. At first read, I thought this was referring to atmospheric stability class, rather than the within-period variation. Recommend making this distinction clear, or using alternative language (i.e. consistent wind conditions). In this section is the CoV calculated over a specific time duration, or is this referring to the r^2 values in Figure 9? Some additional definitions and specificity would benefit this section.
510 & 517: Be specific about “reproducing” and “on par” mean. Does this mean results demonstrating quantification accuracy with a similar order of magnitude? Within XXX%?
Technical Corrections:
244: The authors use both British and American spellings of some words (i.e. modelling & modeling). Please be consistent throughout the manuscript
329: It seems that the ddeq package has a corresponding GMD paper (https://doi.org/10.5194/gmd-17-4773-2024). Add this citation?
480: please define CoV parenthetically.