the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 11 Dec 2025
The Spatial and Temporal Distribution Patterns of XCH₄ in Iran: New Insights from TROPOMI Observations
Abstract. The unprecedented increase in methane concentration, as the second most important greenhouse gas after carbon dioxide, poses a serious challenge to climate change mitigation policies, while accurate and comprehensive monitoring remains insufficient in many countries, including Iran. This study investigates the spatial and temporal patterns of column-averaged methane in Iran using satellite-based observations from Tropospheric Monitoring Instrument on the Sentinel-5P satellite during 2019–2024 and compares them with data from the Emissions Database for Global Atmospheric Research database. On average, XCH₄ concentrations across Iran increased from 1872.6 ± 11.9 ppb in 2019 to 1918.6 ± 11.2 ppb in 2024, representing a +46.1 ± 16.4 ppb rise over six years. All uncertainty estimates represent standard deviations, with a mean value of 12.3 ppb. Statistical and spatial analyses, including Global Moran’s I (0.914–0.982, p < 0.01), Local Moran’s I, and the Getis-Ord Gi* hotspot analysis, confirmed that methane concentrations in Iran exhibit a significant clustering pattern. Hotspots were mainly observed in Class 1: Northern Agro-Hotspots (Gilan, Mazandaran, and Golestan), Class 2: Central Urban-Dense Hotspots, and Class 3: Southern Industrial-Fossil Hotspots, whereas Class 4: Low-Emission Provinces and Class 5: Very-Low-Emission Provinces exhibited lower concentrations with sparse hotspots, located mostly in western and eastern Iran. The highest seasonal averages were recorded in summer (1914.3 ± 13.1 ppb) and autumn (1910.5 ± 13.5 ppb). Comparison with EDGAR data indicates that several major emission sources are underestimated, and spatial overlaps with the observed hotspots did not exceed 5 % in any month. Satellite observations reveal discrepancies in hotspot locations and emission magnitudes, emphasizing that relying solely on modeled inventories may misrepresent methane emissions.
- Preprint
(1944 KB) - Metadata XML
-
Supplement
(907 KB) - BibTeX
- EndNote
Status: final response (author comments only)
-
CC1: 'Comment on egusphere-2025-5852', Argha Ghosh, 11 Jan 2026
-
AC1: 'Reply on CC1', Ali Rahimi, 21 Jan 2026
Thank you very much for your detailed, thoughtful, and highly constructive comments. We sincerely appreciate your positive evaluation of our study and your valuable suggestions, which will greatly enhance the clarity, scientific rigor, and overall quality of the manuscript. We have carefully read the paper you recommended and found it extremely relevant and insightful, and we are truly grateful for this excellent reference.
Your comments regarding methodological transparency, validation between datasets, and the interpretation of spatial variability in methane concentrations in relation to environmental and land-surface drivers are particularly helpful. These suggestions provide important guidance for strengthening both the analytical framework and the discussion of our results. We will carefully address all of your points and incorporate them into the revised manuscript to improve its robustness and impact.
Thank you again for your time and valuable input.
Citation: https://doi.org/10.5194/egusphere-2025-5852-AC1
-
AC1: 'Reply on CC1', Ali Rahimi, 21 Jan 2026
-
RC1: 'Comment on egusphere-2025-5852', Anonymous Referee #1, 01 Feb 2026
Please find the comments in the attached Supplementary file.
-
AC2: 'Reply on RC1', Ali Rahimi, 04 Feb 2026
Dear Referee,
Thank you very much for your valuable comments. We appreciate your careful review and will carefully consider your suggestions in our revision. Your feedback will be taken into account to improve the paper
We are currently revising the paper and will resubmit a fully revised version soon.Best regards,
Ali RahimiCitation: https://doi.org/10.5194/egusphere-2025-5852-AC2
-
AC2: 'Reply on RC1', Ali Rahimi, 04 Feb 2026
-
RC2: 'Comment on egusphere-2025-5852', Anonymous Referee #2, 18 Feb 2026
This manuscript aims to use TROPOMI-based methane information and spatial autocorrelation/hotspot statistics to map and interpret the spatiotemporal distribution of methane over Iran and to compare these patterns with EDGAR. The motivation is generally aligned with the journal's scope; however, the current version lacks several essential elements and contains inconsistencies that require significant improvement before it can be evaluated as a robust scientific contribution.
Overall, I agree with most of Reviewer 1’s scientific/technical concerns, except for the statements regarding LLM-generated text, since I have not done such a test myself and therefore cannot comment on that aspect. However, while reading I identified several inconsistencies and presentation issues (starting from the references and extending into figures and internal cross-references) that hinder confidence in the manuscript.
Major concerns
- References
- The first citation appearing in the manuscript (Saleem et al., 2025) could not be located in the reference list. This should be checked and corrected across the full manuscript.
- Several citations in the Introduction appear to be tertiary or secondary sources for general statements. For foundational introductory points (e.g., general statements about methane and global warming potential), the reference choices feel unusual and weaken the scholarly basis of the paper.
- Data-source referencing follows a similar pattern by non-primary/less-relevent references. Overall, the paper gives the impression of limited engagement with core mission/product literature (for example, key TROPOMI mission or instrument overview references are expected but appear to be missing).
- Figure captions are insufficient
- Many figure captions function only as titles. Captions should contain a short, direct description of what is shown, what dataset is used, what time period is covered, and what the reader should notice. The current captions are often not informative enough for a standalone reading.
- Figure 1b histogram: unclear and possibly incorrect presentation
- The histogram in Figure 1b visually appears odd: the central part of the histogram looks incomplete (missing bars) and the plotted summary statistics are confusing.
- The text claims panel (b) contains annual mean, median, and variability, but the plot shows a ‘mode,’ while the median is not shown. In addition, what is labelled as ‘mode’ does not visually correspond to a typical mode?.
- This figure should be revisited: explain exactly what is plotted.
- Table S5
- The line 300 states: “A notable gap between the mode and other statistical measures suggests the potential presence of a skewed distribution (Table S5).” However, Table S5 does not contain the ‘mode.’
- Clarity and precision
- Some of the explanatory statements read as broad qualitative interpretations without clear supporting evidence or linkage to specific analyses (for example, attributing hotspot regions to particular activity types without an explicit supporting comparison shown in the results).
- The manuscript would benefit from more precise wording and better separation between what is directly supported by the analysis versus what is proposed as interpretation.
Summary recommendation
The study has some potential, but in its current form it reads as loosely prepared and requires significant revision. I therefore recommend rejection at this stage, and I encourage the authors to undertake major revisions (including careful reference checking and figure validation) before resubmission to any journal. The manuscript would also benefit from careful supervision and thorough review by the co-authors to ensure consistency and scientific clarity throughout.
Citation: https://doi.org/10.5194/egusphere-2025-5852-RC2 - References
Viewed
| HTML | XML | Total | Supplement | BibTeX | EndNote | |
|---|---|---|---|---|---|---|
| 284 | 147 | 40 | 471 | 47 | 13 | 13 |
- HTML: 284
- PDF: 147
- XML: 40
- Total: 471
- Supplement: 47
- BibTeX: 13
- EndNote: 13
Viewed (geographical distribution)
| Country | # | Views | % |
|---|
| Total: | 0 |
| HTML: | 0 |
| PDF: | 0 |
| XML: | 0 |
- 1
The Manuscript contains substantial research findings on the tropospheric methane concentration and hotspot identification. However, inclusion of some additional information would enhance the quality and clarity of the research as follows:
1. The process of hotspot identification was described in a very qualitative manner like using higher or lower values in Section 2.3.2. For better understanding and clarity the exact threshold values for differentiating the higher and lower values should be mentioned. A table representing the high and lower threshold values may be added.
2. Cite proper references for Global and Local Spatial Autocorrelation Analysis and hotspot analysis.
3. The validation between the two data source may be shown.
4. The research shows methane concentration over an entire country. Therefore, some reasons behind the high or low concentration should be included (with respect to hydro-meteorological variables, topographic variation, land use pattern etc. because these influence the methane concentration). Methane concentration pattern over different land use or topographic regime may be shown. The author can follow similar research if found suitable (https://doi.org/10.1007/s41324-025-00666-5).