the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Multi-annual temperature evolution and implications for cave ice development in a sag-type ice cave in the Austrian Alps
- 1Department of Atmospheric and Cryospheric Sciences, University of Innsbruck, Innsbruck, 6020, Austria
- 2Institute of Geology, University of Innsbruck, Innsbruck, 6020, Austria
- 1Department of Atmospheric and Cryospheric Sciences, University of Innsbruck, Innsbruck, 6020, Austria
- 2Institute of Geology, University of Innsbruck, Innsbruck, 6020, Austria
Abstract. Ice caves are, similar to mountain glaciers, threatened by the warming climate. To better understand the response of perennial ice in caves to a changing climate, we analysed the thermal characteristics of a sag-type ice cave in the Austrian Alps (Hundsalm ice cave), based on long-term temperature measurements for the period 2008–2021. Observations show a warming trend in all parts of the cave as well as a distinct seasonal pattern with two main regimes, i.e., an open (winter) and a closed (summer) period. During the closed period, a persistent stable stratification prevails that largely decouples the cave from the external atmosphere. The open period is characterised by unstable to neutral stratification and allows episodic penetrations of cold air from outside into the cave interior. Vertical temperature profiles also provide hints on corresponding circulation patterns and the spatial temperature variability in the cave. The positive air temperature trend is reflected in a decrease in perennial cave ice, derived from stake measurements. Besides surface melting, we find compelling evidence of basal melting of ice. The observed ablation rates can be well reproduced by applying a modified degree-day model, which, however, is less feasible regarding mass balance. Overall, we conclude that Hundsalm ice cave is highly impacted by regional warming which will lead to the disappearance of its perennial ice deposits within the next decades.
Maria Wind et al.
Status: open (until 31 May 2022)
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RC1: 'Comment on tc-2022-67', Anonymous Referee #1, 29 Apr 2022
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GENERAL COMMENTS
Dear Editor,
I’ve read the manuscript “Multi-annual temperature evolution and implications for cave ice development in a sag-type ice cave in the Austrian Alps” by Wind et al.
I found the manuscript an interesting submission describing fully and comprehensively the microclimate of a sag-type ice cave. The manuscript fits with the purpose of the journal TC.
The manuscript reports significant information generally poorly or not addressed in the existing literature and it is, therefore, a valuable work.
Although pointed out several times and accurately described, the only “weakness” of the work relates to the lack of data calculating the impact of visitors in the cave, which is indeed something hard to quantify. This is not something that affects the quality of the paper itself but makes the findings a bit less important than what could have been achieved in a non-touristic cave.
Besides such general comments and the specific comments below, I suggest the manuscript can be published after minor revision.
SPECIFIC COMMENTS
P 2 L 30-35: as I agree with the statement “it is crucial to assess and understand the microclimatic and glaciological conditions inside ice caves and their coupling to the outside atmosphere” I suggest the innovative CFD model approach proposed by Bertozzi et al., (2019) “On the interactions between airflow and ice melting in ice caves: A novel methodology based on computational fluid dynamics modelling” https://doi.org/10.1016/j.scitotenv.2019.03.074, 2019 is mentioned in this section.
Figure 1: for more clarity, I suggest adding the location of the stakes even in the elevation view (lower panel)
P 5 L 106 (also related to P20 L 416-419): I understood that, as you mentioned, it is really hard to quantify the effects of artificial snow input inside the cave, but can you be more specific about this process? I see that some information is retrievable from Fig. 8 and some are explained in the discussions but maybe you can add some more if known. For example: is the snow input affecting all the areas homogeneously or just near the entrances, how often does it happen usually, just in late winter? Has the artificial snow input ever been quantified at least in snow thickness at a stake to have a vague idea of its impact (maybe referring to some of the Figure 8 values)? Is the shovelling process documented every time or the listed markers are just some of them?
P21 L 430-437: I feel that having a range of values from other stakes and T sensors would enrich the discussions of this work and improve the eventual future comparisons with other studies using this methodology in different caves. I understand that stake B and T29 were used as references for deriving the DDF as they are more robust. Is there a chance that some other T sensors and stakes are used for calculation of shorter DDF periods and then compared with the reference values that you already mentioned? If stake B is affected by the artificial snow input, are there other stakes that can be less affected by snow shovelling and therefore can provide additional data in the discussion of DDF findings?
Maria Wind et al.
Maria Wind et al.
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