Insights into Sea Spray Ice Adhesion from Laboratory Testing

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The paper investigates adhesion strength of sea spray ice experimentally. Sea spray icing is simulated under controlled laboratory environment and adhesion is measured with varying growth conditions, sample geometry, ice thickness and brine layer thickness. The paper presents the related theoretical background, the experimental set-up, and a detailed presentation and discussion of the results. The topic is of interest, and the paper demonstrates that the authors carried out a thorough investigation. The drawback is that the results could not reveal the relationships that were expected between the adhesion strength and some of the parameters examined. The statistical analysis and discussion is too much detailed, without the benefit that could be expected. It is clear that the adhesion of ice formed from seawater is about an order of magnitude smaller than that formed from freshwater. However, this was already known, and the study failed to reveal a dependence of adhesion strength on temperature or salinity. On the other hand, it was found that adhesion depends on edge length or sample size. This geometrical property is a parameter describing the experimental set-up, but not the natural conditions, so it is not clear what the information is from this result to practical applications. Further issues are the following.

1. Eq. (2): What does 3D/L mean physically? How was this correction obtained?
2. Eqs. (6) and (7): According to the text, both of Eqs. (6) and (7) are valid between 18 and 50 per mille. Which one of them should be used in this interval?
3. Line 199: “Thus, the brine layer thickness would be increasing with the specific surface.” How can this conclusion be drawn? The thickness d_b decreases when specific surface A/V increases according to Eq. (20). Even the thickness H decreases with increasing A/V according to Eq. (23).
4. Figure 3: Why is the variation in the temperature of samples S1-S4 in the period of preparation? If they are exposed to air only (no spray), then why is their temperature not the same as the air temperature?
5. Section 3.4: A figure about the adhesion measurement would help understand how the measurement was carried out, at least increasing the relevant part in Figure 2(b). The speed 14 mm/s seems quite high. When the actuator moves so quickly, how can the authors decide if ice is removed when the force exceeds adhesion or when it exceeds cohesion?
6. The discussion in Section 5 begins with claiming that “results demonstrate that sea spray ice exhibits an order of magnitude lower adhesion strength compared to freshwater ice”, but the adhesion of sea spray ice were compared to that of freshwater ice only later.
7. Equations (25) to (28) are proposed to estimate adhesion and thickness. They are concluded in Section 5; however, it is not explained or demonstrated how they are obtained. Authors should refer to corresponding equations in the theory or compare calculations using these equations with experimental results.

Further minor comments, typos:

8. There are some typing errors in the manuscript, e.g. Line 101: "the contribution” occurs twice; Line 104: “where” should be “were”; there are missing verbs in Line 459 and in Line 460.
9. Fig. 3(e) shows an experiment at -15C, but the text in Line 265 claims that the air temperature is -10C in Fig. 3(a) to 3(d). Is the air temperature not the same in Fig. 3(a) to 3(e)?
10. Section 3.5: The X-ray micro-tomographic scanning is detailed in Section 3.5, but the goal of this measurement should also be mentioned.
11. Figure 10: Captions for Figures 10(b) and 10(c) are interchanged.
12. Figure 14: Scale bar is not legible.
13. Line 630: There is no Table 5.2.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

(1) What is the basis for selecting the low temperature range for testing? Please provide the author with a detailed explanation.
(2) Does sea spray medicine contain salt? How is the salinity range determined? Please provide the author with a detailed explanation. And before sea ice freezes, there will be a process of salt analysis. Did the author consider this in the testing?
(3) How many parameters, such as water drop diameter and spray speed, are tested by the author? How do these parameters affect the experimental test results? Please provide the author with a detailed explanation.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors considered the comments and questions, and revised the manuscript thoroughly. This reviewer’s two main concerns were responded, and the manuscript has been properly revised to explain the practical implications of the geometrical aspects. The argument about the significance of the results in spite of that correlations between adhesion strength and temperature or salinity were not observed is also acceptable. However, the authors’ response should also be involved in the conclusions, even if in a different form:

“It suggests that within the tested parameter space the influence of temperature and salinity on adhesion strength may be secondary to other microstructural or interfacial factors, such as brine expulsion dynamics and interface geometry. The absence of correlation under controlled growth conditions helps refine our understanding of the complexities involved in sea spray ice formation and adhesion and supports the opinion that saline ice adhesion behavior is not solely governed by bulk salinity or ambient temperature.”

Furthermore, two typos were noticed in the text added:

1. Lines 122-123: Do you mean "the fraction of the salt mass and the total mass of the ice sample"?
2. Line 902: The verb “see” is doubled.

Author Response

Response to the reviewers’ comments

 

Manuscript ID: thermo-3730921

Title: Insights into sea spray ice adhesion from controlled testing

 

We are very grateful to the reviewers for the time, effort and the kind comments! The manuscript has carefully been revised according to the recommendations. Changes are highlighted in the revised manuscript.

 

The authors considered the comments and questions, and revised the manuscript thoroughly. This reviewer’s two main concerns were responded, and the manuscript has been properly revised to explain the practical implications of the geometrical aspects.

 

We again thank you for the thoughtful comments that helped us to improve the manuscript.

 

The argument about the significance of the results in spite of that correlations between adhesion strength and temperature or salinity were not observed is also acceptable. However, the authors’ response should also be involved in the conclusions, even if in a different form:

 

“It suggests that within the tested parameter space the influence of temperature and salinity on adhesion strength may be secondary to other microstructural or interfacial factors, such as brine expulsion dynamics and interface geometry. The absence of correlation under controlled growth conditions helps refine our understanding of the complexities involved in sea spray ice formation and adhesion and supports the opinion that saline ice adhesion behavior is not solely governed by bulk salinity or ambient temperature.”

 

We certainly agree with the reviewer that the response can be better implemented in the conclusion. Therefore, we expanded the paragraph about the processes involved in adhesion strength of sea spray ice in the conclusion.  

 

Furthermore, two typos were noticed in the text added:

1. Lines 122-123: Do you mean "the fraction of the salt mass and the total mass of the ice sample"?

Yes, I was supposed to be “the fraction of the salt mass and the total mass of the ice sample”, we changed it accordingly.

1. Line 902: The verb “see” is doubled.

The advice has been taken.

 

Additionally we checked the manuscript for more typos and changed:

• “correllation” to “correlation” in line 672,
• “porisometry” to “porosimetry” in line 553
• added “for fresh ice [56,57] and sea ice [58,59] and one would expect this for sea spray ice also “ in line 756 as it was not displayed in the previous version due to wrong latex command used for highlighting