the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
The ISLAS2020 field campaign: Studying the near-surface exchange process of stable water isotopes during the arctic wintertime
Abstract. The ISLAS2020 field campaign during February and March 2020 set out to obtain a unique dataset describing the Arctic water cycle using stable water isotope (SWI) observations. Our observation strategy focused on measuring evaporation, deposition, and precipitation, all of which are commonly sub-grid scale processes in numerical weather and climate models. Uncertain parameterizations for these processes can lead to compensating errors, which can go unnoticed; however, evaporation and precipitation can also be investigated with SWIs, as they are an integrated tracer for processes that atmospheric moisture has undergone. The campaign can be divided into two efforts: the primary field experiment in Ny-Ålesund focused on evaporation and deposition, and the larger precipitation collection network around the Nordic Seas.
The primary field experiment lasted three weeks, from 23 February to 15 March 2020, with temperatures reaching below −30 °C. During these weeks, we obtained near-surface, high-resolution (approx. 20 cm) SWI profiles at two deployment sites. Using a newly developed profiling system, we measured SWI gradients in the lowermost 5 and 2 m over fjord water and snow-covered tundra, respectively. These profiles are complemented by fiber-optic distributed sensing (FODS) columns and nearby meteorological stations. The FODS columns supply continuous, high-resolution (2 cm or finer) temperature profiles above both locations, whereas the meteorological stations provide information on wind speed and direction. We also made a short deployment to the Zeppelin mountain observatory (472 m a.s.l) for measurements of the isotopic signal in the free-troposphere. Additionally, numerous water samples from the snowpack in and around Ny-Ålesund were taken, in addition to daily fjord water samples from Kongsfjorden. These samples provide the context for the surface conditions under which profiles were collected. Isotopic connections on the synoptic scale are achieved by linking Ny-Ålesund observations with precipitation sampling at locations across the European Arctic, namely Longyearbyen, Tromsø, Andenes, Ålesund, and Bergen. The resulting dataset provides comprehensive insight into the Arctic hydrological cycle and can facilitate the study of phase change processes and transport of water vapour into and out of the Svalbard region. Datasets from the field campaign are publicly available at the PANGAEA data repository (https://doi.pangaea.de/10.1594/PANGAEA.971241, Seidl et al., 2024).
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Status: final response (author comments only)
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RC1: 'Comment on essd-2024-293', Anonymous Referee #1, 29 Nov 2024
- AC1: 'Reply on RC1', Andrew Walter Seidl, 23 May 2025
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RC2: 'Comment on essd-2024-293', Anonymous Referee #2, 05 Feb 2025
General comments:
This paper presents water isotope data collected during the ISLAS202 campaign. These stable isotope data include multiple different water phases (e.g., liquid, vapor, solid-snow, ice, etc.) from both inland and coastal settings. Overall, the study design and data collection methods are sound and the data seem of high quality, especially given the difficulties of doing this type of work (the water vapor data, in particular) in the High Arctic. The data presented by the authors is likely to be of use to various different disciplines from climate modelers to cryosphere scientists. The vertical profile data are particularly innovative and of interest. With some minor revisions, this manuscript could be acceptable for publication in Earth System Science Data.
More specific comments:
Lines 48-50: Adding some recent (existing) work showing how different process and locations influence variability in Arctic d-excess would be beneficial. While more Arctic d-excess information (as in this paper) would certainly be helpful, recent work reveals some of this nuance that the authors state as needed and should be included. This would also help place the contributions of this work in better context.
For example:
Wahl, S., Walter, B., Aemisegger, F., Bianchi, L., & Lehning, M. (2024). Identifying airborne snow metamorphism with stable water isotopes. The Cryosphere, 18(9), 4493-4515. Indicates how water vapor d-excess can change with varying snow and (Arctic) atmospheric conditions (e.g., temperature, wind, etc.) in a laboratory setting.
Klein, E. S., Baltensperger, A. P., & Welker, J. M. (2024). Complexity of Arctic Ocean water isotope (δ18O, δ2H) spatial and temporal patterns revealed with machine learning. Elementa: Science of the Anthropocene, 12(1). Reveals nuance and new spatial patterns in Arctic d-excess values.
With this set up, the authors can then more specifically describe their new contributions to understanding d-excess variability (some of which begins at Line 59) and place them in better context. For example, the vertical profiles and quite creative and interesting.
Line 127-128: The authors state that daily samples were taken, entirely of snow. What if there was not any fresh snow? Were samples collected from the existing surface? Was this done in the same spot (after several days of collection, samples would be further down the snow pack and not near the surface)?
Line 132: In this context, please explain high frequency. Once a day? Twice a day?
Line 188: Is the tubing flow path length the same at 4 cm as 200 cm? Due to logistics, I suspect so, but this would be good to clarify. Were the flow rates the same at all heights?
Line 280: Why was the plastic tubing a combination of Bev-A-Line (~4m) and PTFE tubing (~6m)? I don’t think this matters for data collection and I understand the challenges of working in the field, but I was just wondering if there was a particular reason for this.
Lines 322-324: It looks like with the secondary standards used for water vapor isotope calibration, DI and GSM1, the most depleted (negative) value is -261 ‰ for δD. However, if I am interpreting this correctly, some of the values are far below this (e.g., Figure 6 from the snow tundra site has values below -340).
Is there a reason a standard with a lower value was not used? Table 6 lists GLW, which has a lower value, but it appears this was not used for vapor? Is there a reason a standard with a lower value was not used for calibration and how might this impact the values (e.g., potentially greater error with more depleted values)?
Also, this is somewhat subjective, but there are many uses of passive voice, which make the paper longer and more difficult to read. For example, in the first sentence of Section 2, the word “being” can be deleted between “site” and “in”.
Citation: https://doi.org/10.5194/essd-2024-293-RC2 - AC2: 'Reply on RC2', Andrew Walter Seidl, 23 May 2025
Data sets
Calibrated stable water isotope measurements from Svalbard and coastal Norway during February and March 2020 [dataset bundled publication] Andrew Walter Seidl et al. https://doi.pangaea.de/10.1594/PANGAEA.971241
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Review of Seidl et al. “The ISLAS2020 field campaign: Studying the near-surface exchange process of stable water isotopes during the arctic wintertime” submitted to ESSD
This paper describes an extensive effort of water sample collection for isotope analysis in the Arctic during an exceptionally cold period in late winter 2020 with 11 near-surface profiles over a snow covered and an open ocean surface in Ny Ålesund as well as many precipitation samples from different location in Svalbard and along the coast on the Norwegian mainland. To me the near-surface profile data is truly innovative and interesting and the whole dataset provides exciting new insights into moisture cycling in the Arctic. I find the paper well written and very well documented. In some instances, the descriptions are a bit too detailed and lengthy, but in general I found the paper to be well-balanced. I would suggest providing an earlier overview figure of the sampled data together with the meteorological documentation at the beginning of the paper. Otherwise, the data and methods section is very challenging to read. But this can be easily solved by placing Fig.9 and 10 much earlier and relating them to Fig. 2 with the meteorological overview. I also recommend some more in-depth discussion of the isotope observations in the profiles to provide some physical consistency checks since the deuterium excess observations are indeed far from the normal range of expected measurements. Below you find some more detailed comments.
Minor comments:
Kirbus, B., Schirmacher, I., Klingebiel, M., Schäfer, M., Ehrlich, A., Slättberg, N., Lucke, J., Moser, M., Müller, H., and Wendisch, M.: Thermodynamic and cloud evolution in a cold-air outbreak during HALO-(AC)3: quasi-Lagrangian observations compared to the ERA5 and CARRA reanalyses, Atmos. Chem. Phys., 24, 3883–3904, https://doi.org/10.5194/acp-24-3883-2024, 2024.
Papritz, L., Rouges, E., Aemisegger, F., & Wernli, H. (2019). On the thermodynamic preconditioning of Arctic air masses and the role of tropopause polar vortices for cold air outbreaks from Fram Strait. JGR, 124, 11033–11050. https://doi.org/10.1029/2019JD030570
Brunello, C.F., Gebhardt, F., Rinke, A., Dütsch, M., Bucci, S., Meyer, H., et al. (2024). Moisture transformation in warm air intrusions into the Arctic: Process attribution with stable water isotopes. Geophysical Research Letters, 51, e2024GL111013. https://doi.org/10.1029/2024GL111013
And in the Southern Ocean:
Thurnherr, I. and Aemisegger, F.: Disentangling the impact of air–sea interaction and boundary layer cloud formation on stable water isotope signals in the warm sector of a Southern Ocean cyclone, Atmos. Chem. Phys., 22, 10353–10373, https://doi.org/10.5194/acp-22-10353-2022, 2022.
Hu, J., Yan, Y., Yeung, L. Y., & Dee, S. G. (2022). Sublimation origin of negative deuterium excess observed in snow and ice samples from McMurdo Dry Valleys and Allan Hills Blue Ice Areas, East Antarctica. Journal of Geophysical Research: Atmospheres, 127, e2021JD035950.
Interestingly this profile was sampled during a CAO period over Fram strait. But the profiles with stable stratification for most of the time show that locally the site is influenced by a mesoscale wind system apparently advecting relatively warmer subsiding air over the snow site. I think these aspects should be highlighted because they matter for the credibility of the observations presented, which do deviate somewhat from the normal observational range for the dexcess.
Casado, M., Landais, A., Picard, G., Arnaud, L., Dreossi, G., Stenni, B., & Prié, F. (2021). Water isotopic signature of surface snow metamorphism in Antarctica. Geophysical Research Letters, 48, e2021GL093382. https://doi.org/10.1029/2021GL093382
Aemisegger, F., Trachsel, J., Sadowski, Y., Eichler, A., Lehning, M., Avak, S., & Schneebeli, M. (2022). Fingerprints of frontal passages and post-depositional effects in the stable water isotope signal of seasonal Alpine snow. Journal of Geophysical Research: Atmospheres, 127, e2022JD037469. https://doi.org/10.1029/2022JD037469