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https://doi.org/10.5194/essd-2025-805
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/essd-2025-805
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
10 Mar 2026
| 10 Mar 2026
Status: this preprint is currently under review for the journal ESSD.
Global Water Vapor Stable Isotope Dataset
Abstract. Stable isotopes in atmospheric water vapor (reported as H and O relative to VSMOW) provide valuable constraints on moisture sources, transport, and phase-change fractionation. Yet available observations remain fragmented across platforms, regions, and time periods, and cross-study comparison is often hindered by inconsistent metadata, calibration reporting, and quality-control practices. Here we compile and harmonize a global near-surface water vapor isotope dataset from three sources: the WaterIsotopes Database (wiDB; http://wateriso.utah.edu/waterisotopes), PANGAEA (https://www.pangaea.de), and peer-reviewed literature. The dataset spans 1981–2021 and contains 87,138 records from 112 sites/platforms. We standardized coordinates to WGS84, timestamps to UTC when possible, isotope units to per mil (‰) in delta notation, and compiled measurement metadata (instrument, method, and model where explicitly reported; e.g., Picarro CRDS, LGR OA-COS, IRMS following cryogenic trapping, and satellite retrieval products). A transparent quality-control workflow was applied to identify duplicates, inconsistent metadata, and implausible or poorly documented values, while preserving traceability to original sources. The resulting product provides a consistent observational basis for model evaluation and for comparative studies of water vapor isotope variability across climates and observation strategies. The Global Water Vapor Stable Isotope Dataset is available at https://doi.org/10.6084/m9.figshare.30893984 (Zhu and Yang, 2025).
How to cite. Yang, D., Zhu, G., Yang, J., Li, R., Wang, Q., Su, X., Lei, Y., Zhang, Y., Liu, W., Ning, K., Wang, X., and Li, Y.: Global Water Vapor Stable Isotope Dataset, Earth Syst. Sci. Data Discuss. [preprint], https://doi.org/10.5194/essd-2025-805, in review, 2026.
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Global Water Vapor Stable Isotope Dataset Dongfei Yang et al. https://doi.org/10.6084/m9.figshare.30893984
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Dongfei Yang
College of Geography and Environment Science, Northwest Normal University, Lanzhou 730070, Gansu, China
Shiyang River Ecological Environment Observation Station, Northwest Normal University, Lanzhou 730070, Gansu, China
Key Laboratory of Resource Environment and Sustainable Development of Oasis, Gansu Province, Lanzhou 730070, Gansu, China
College of Geography and Environment Science, Northwest Normal University, Lanzhou 730070, Gansu, China
Shiyang River Ecological Environment Observation Station, Northwest Normal University, Lanzhou 730070, Gansu, China
Key Laboratory of Resource Environment and Sustainable Development of Oasis, Gansu Province, Lanzhou 730070, Gansu, China
Lanzhou Branch, Remote Sensing Application Center, Ministry of Agriculture and Rural Affairs, Lanzhou 730070, Gansu,China
Jiangwei Yang
College of Geography and Environment Science, Northwest Normal University, Lanzhou 730070, Gansu, China
Shiyang River Ecological Environment Observation Station, Northwest Normal University, Lanzhou 730070, Gansu, China
Key Laboratory of Resource Environment and Sustainable Development of Oasis, Gansu Province, Lanzhou 730070, Gansu, China
Rui Li
College of Geography and Environment Science, Northwest Normal University, Lanzhou 730070, Gansu, China
Shiyang River Ecological Environment Observation Station, Northwest Normal University, Lanzhou 730070, Gansu, China
Key Laboratory of Resource Environment and Sustainable Development of Oasis, Gansu Province, Lanzhou 730070, Gansu, China
Qinqin Wang
College of Geography and Environment Science, Northwest Normal University, Lanzhou 730070, Gansu, China
Shiyang River Ecological Environment Observation Station, Northwest Normal University, Lanzhou 730070, Gansu, China
Key Laboratory of Resource Environment and Sustainable Development of Oasis, Gansu Province, Lanzhou 730070, Gansu, China
Xiaoxiao Su
College of Geography and Environment Science, Northwest Normal University, Lanzhou 730070, Gansu, China
Shiyang River Ecological Environment Observation Station, Northwest Normal University, Lanzhou 730070, Gansu, China
Key Laboratory of Resource Environment and Sustainable Development of Oasis, Gansu Province, Lanzhou 730070, Gansu, China
Yitian Lei
College of Geography and Environment Science, Northwest Normal University, Lanzhou 730070, Gansu, China
Shiyang River Ecological Environment Observation Station, Northwest Normal University, Lanzhou 730070, Gansu, China
Key Laboratory of Resource Environment and Sustainable Development of Oasis, Gansu Province, Lanzhou 730070, Gansu, China
Yurou Zhang
College of Geography and Environment Science, Northwest Normal University, Lanzhou 730070, Gansu, China
Shiyang River Ecological Environment Observation Station, Northwest Normal University, Lanzhou 730070, Gansu, China
Key Laboratory of Resource Environment and Sustainable Development of Oasis, Gansu Province, Lanzhou 730070, Gansu, China
Wenjing Liu
College of Geography and Environment Science, Northwest Normal University, Lanzhou 730070, Gansu, China
Shiyang River Ecological Environment Observation Station, Northwest Normal University, Lanzhou 730070, Gansu, China
Key Laboratory of Resource Environment and Sustainable Development of Oasis, Gansu Province, Lanzhou 730070, Gansu, China
Kang Ning
College of Geography and Environment Science, Northwest Normal University, Lanzhou 730070, Gansu, China
Shiyang River Ecological Environment Observation Station, Northwest Normal University, Lanzhou 730070, Gansu, China
Key Laboratory of Resource Environment and Sustainable Development of Oasis, Gansu Province, Lanzhou 730070, Gansu, China
Xinyue Wang
College of Geography and Environment Science, Northwest Normal University, Lanzhou 730070, Gansu, China
Shiyang River Ecological Environment Observation Station, Northwest Normal University, Lanzhou 730070, Gansu, China
Key Laboratory of Resource Environment and Sustainable Development of Oasis, Gansu Province, Lanzhou 730070, Gansu, China
Yaxin Li
College of Geography and Environment Science, Northwest Normal University, Lanzhou 730070, Gansu, China
Shiyang River Ecological Environment Observation Station, Northwest Normal University, Lanzhou 730070, Gansu, China
Key Laboratory of Resource Environment and Sustainable Development of Oasis, Gansu Province, Lanzhou 730070, Gansu, China
Short summary
To understand where air moisture comes from and how it changes, we created an open global collection of 87,138 measurements of natural chemical signatures in water vapor from 112 locations, covering 1981 to 2021. We gathered records from papers and public archives, then checked, cleaned, and standardized the values, dates, locations, and methods. This baseline can improve weather and climate models and help track water cycle change.
To understand where air moisture comes from and how it changes, we created an open global...
Altmetrics
Review of "Global Water Vapor Stable Isotope Dataset" Yang et al., submitted to ESSD
The authors describe a dataset of water vapour isotope measurements that they claim has been compiled from existing literature and published datasets. A brief check of the the data therein, including publications to which this reviewer contributed, shows that for example, precipitation data is being misrepresented as vapour data, and that also other essential metadata has been lost during the compilation process. While I think it is in general useful to work on homogenising and compiling existing datasets, the present study lacks scientific rigour, and even basic quality control to an extent that in my opinion does not meet the requirements for the study to be publishable in ESSD. The accompanying dataset should be retracted or at least revised to exclude all erroneous data points. My detailed comments are included below.
In the introduction, the authors state that they provide compiled water vapour isotope data, but their dataset, apparently without noticing, lumps together precipitation and vapour measurements. Due to isotope fractionation between vapour and liquid, this error is so severe that the dataset becomes useless when the two data categories are mixed together, and will even lead to wrong conclusions if used by others. Examples from their dataset include, but are not limited to data points described in Chazette et al., (2021), as well as from the dataset described in the publication by Seidl et al. (2024).
The stable isotope values in the data file are often given with 5 or more digits, far beyond any reasonable measurement precision, in particular for the delta D where it is common to report with 1 digit precision. It is unclear how these data points were derived, but they are not provided in the referenced publications. Possibly the data points were digitised from publication figures? If so, this must be specified in the methods, but see below.
It is never explained how the data from references have been obtained exactly, and from point (2) above, it seems that they have been digitised from figures in existing publications. This reviewer finds it worrying that the authors did not simply contact the corresponding authors of the studies they wanted to compile the data from, which should be the first step before possibly considering to digitise and re-publishing data from published papers. When data has indeed been digitised from existing publications that results in a different precision, questions of copyright compliance and data validity need to be addressed.
Traceability and crediting of scientific works: The authors claim to have used very many sites ("and 4,421 literature-derived records from 85 observation sites") to source their data, but the data set only contains data from 31 papers. It should be no problem space-wise and would do due credit to explicitly cite all these studies in a summary table in the main manuscript, for example by listing the time range and number of samples of each paper. The website waterisotope.org is just a portal, so here the authors still should cite the original sources of the studies that produced the data.
The data file that the authors compiled lacks essential metadata. Only a single time is given per data point, so it is unknown what time interval this data should represent. The description in the paper is inconsistent with what is provided in the data file. The authors state that they computed the d-excess, but this information is not included in the data tables. Also information about instrument type and method are not included in the data tables, contrary to what is said in the manuscript.
This reviewer notes that the set-up and figures in this paper are very similar to a study on surface water samples that has been published last year in ESSD (Li et al., 2025). The similarity to that study would need to be pointed out and addressed in the manuscript.
Fig. 3a has a reversed time axis.
The table in the appendix contains the same errors as in the data set regarding the mix-up between vapour and precipitation data noted above.
Figure 2 contains a "Calibration and consistency" step - it is not explained what would be done here. All published data that is referenced were already calibrated, why should this happen at the end of merging the datasets?
Since the dataset lumps together vapour and precipitation data, Fig. 4 and Fig. 5 are meaningless. Fig. 4c has a suspicious high d-excess at geographical coordinate 0ºN, 0ºE which is possibly an artefact from missing geographic coordinates.
References
Li, R., Zhu, G., Chen, L., Qi, X., Lu, S., Meng, G., Wang, Y., Li, W., Zheng, Z., Yang, J., and Gun, Y.: Global Stable Isotope Dataset for Surface Water, Earth Syst. Sci. Data, 17, 2135–2145, https://doi.org/10.5194/essd-17-2135-2025, 2025.