General comments

This manuscript presents a detailed analysis of three atmospheric rivers affecting Svalbard during May – June 2017. A number of observational, reanalysis, and satellite datasets are used to analyze the events and the consistency between these data sources is assessed. A strength of this paper is its detailed comparison of two different AR detection algorithms, including an assessment of “potential AR” events that are hydroclimatically significant but may miss detection by the geometric criteria of certain AR algorithms. The potential impact of these events in the Arctic is a topic that has not been well explored in the literature. The detailed evaluation of several different reanalysis datasets and the HIRHAM model is also a strong contribution to the field, particularly the assessment of vertical profiles of wind and humidity. The paper is very well referenced with the appropriate literature. I have a few minor suggestions that I feel would further strengthen this work, including some quantitative validation of the various datasets and further discussion of the HIRHAM model deficiencies. Pending these minor revisions and the correction of some grammatical items as detailed below, I feel this paper will be suitable for publication in ACP.

Specific comments

This paper has a lot of nice qualitative discussion of the differences observed among the various reanalysis and model datasets and their comparison to observations. However, quantitative assessment of these datasets is lacking. I think that providing and discussing some simple summary statistics (e.g. RMSE, bias) comparing the most important parameters that are available from both the model/reanalysis datasets and observations (IWV, IVT, wind speed) would strengthen the paper and increase its value to other researchers. 

A notable feature of the results is the poor performance of the HIRHAM model compared to the reanalysis datasets, including the ERA-Interim dataset that it was forced with. This result is somewhat surprising to me since this model has high spatial and vertical resolution and has been extensively used in Arctic climate studies. I think the paper would benefit from some additional discussion of why the HIRHAM model performed so poorly. Have problems with the HIRHAM wind and humidity fields been documented in other studies? Do the authors think this may be an issue with how HIRHAM was implemented in this particular case or a more general problem with the model?

L31: Does “the model” here refer to a deficiency in the performance of the HIRHAM model specifically, or to all the reanalysis products?

L207: The purpose and application of the successively increasing IVT percentile thresholds in the Guan algorithm are not clear from this description. How is the AR area ultimately determined from this procedure? Some additional description here would be useful. 

L281-282: What makes the Guan algorithm less restrictive compared to the polar-specific algorithms? Could the differences in algorithms have to do with using IWV (Gorodetskaya) versus IVT (Guan) for AR detection?

Technical corrections

L11: Specify that *atmospheric* moisture content has increased.

L19: Define what AWIPEV is an abbreviation for.

L43: “On contrary” --> “On the contrary”

L44: Does this refer to an increase in the severity of winter weather events or in overall winter seasons?

L71: Specifically, ARs have been shown to influence the mass budget of *ice sheets* in the Arctic and Antarctic.

L84: “on” --> “of”

L90: Remove the word “study” from this sentence.

L92: “point” --> “pointed”

L96: “resultant of” --> “resulting from”

L111: “does it identify” --> “it identifies”

L117: “suit” --> “suite”

L147: “exception” --> “the exception”

L156: “cyclones” --> “cyclone”

L222: “on” --> “of”

L227: “is” --> “are”

L301: I think this sentence describes figure 4 rather than figure 3.

L305 and elsewhere: “associated to” should be changed to “associated with”.

L307: “phenomena” --> “phenomenon”

L356: “previous” --> “prior”

L394: “this type” --> “these types”

L412: I think a different word choice than “approximation” should be used here. Is this referring to the “approach” or “arrival” of the AR to Svalbard?

L420: Remove the word “the” before 850 hPa.

L506: The word “foehn” does not need to be capitalized.

L584: “big” --> “large”

L586: “bigger” --> “larger”

General comments:

This paper explores the differences of atmospheric rivers’ characteristics and meteorology in reanalyses and the regional climate model HIRHAM5 in Svalbard. Using field campaign identification of water vapor transport events in May and June 2017, 3 independent atmospheric river events were detected at a research station over an 11-day period. This paper analyzes how using integrated vapor transport versus integrated water vapor affects atmospheric river detection. Additionally, the differences between reanalyses, the regional climate model, and observations demonstrate the importance of using a high spatial and temporal resolution model for AR identification. This paper was a thorough study in how applications of AR detection schemes vary in the Arctic, where lower atmospheric moisture content must be considered. Additionally, the synoptic and precipitation analyses were very interesting, particularly how the results varied amongst the reanalyses. There were some points that needed clarification, but overall, the manuscript was scientifically interesting, novel, and important work. For these reasons, I am recommending this manuscript for acceptance to ACP with minor revisions.

Specific comments:

Section 3.2: Some added clarification on which datasets the algorithms were applied to would be helpful. The final two sentences (L208-210) specifically state that the Guan2018 algorithm was only applied to MERRA-2, but I was confused until getting into the results about which datasets Gorodetskaya2020 was applied to. It is not stated until L230-231.

L 228-230: Why were these specific datasets chosen to display in Figure 2, when you also applied Gorodetskaya2020 to JRA55 and CFSv2?

L 242-244: While it is later elaborated on in L272-277, it might be helpful to mention, after stating that the geometrical criteria was applied, that the current geometrical applications of the algorithm prevent the June 6 case from being identified as an AR (and is instead a pAR).

Figure 3: Yellow color is difficult to see - could this be changed to a darker yellow?

L 383-384, Figure S7: Should this also be the beginning of the second event? You are referencing the band of high IVT, which appears nearest to Ny-Ålesund at 12 UTC on June 6. 

Figure 7: These figures could probably be made wider by cutting whitespace on the edges to make the timestamps more clear.

Technical comments:

L 301: Should be “Figure 4” not “Figure 3”

L 317: “Siberia” not “Siberian”

L 539: “These were associated” not “These was associated”

The paper by Viceto et al. 2021 analyses three atmospheric river events which took place during the ACLOUD/PASCAL campaigns near Svalbard. They compare model simulations, with a wide variety of reanalysis datasets and observations. In addition, they use two different detection methods for Atmospheric rivers, besides looking at the synoptic situation and vertical profiles. This paper provides an in-depth analysis of those events and provides extra insights of moisture intrusions to this specific region of the Arctic. I found the analysis well done and results well described. In my opinion, the paper could improve in readability by reducing the length of the abstract and summary/conclusions, and by stating more clearly the research questions and uniqueness of the study. By doing so the paper will be easier to read and the main message will appear more clearly. I explain those comments below, together with some minor comments on the paper.

Abstract

Is it needed to mention the dates of the field campaign in sentence 17, for me it would be enough to indicate the dates of the events which fall within the field campaign.

Can you indicate the research question/objective more clearly in the abstract? And as well in the introduction?

Line 21-25; is all this information needed in the abstract or can you reduce the text here?

Line 33: there was an increase of values with height. This ‘of values’ is not really clear. Can you improve this sentence?

Line 35: ..during spring and beginning of summer ..

Minor comments

Line 53: reasons

Line 55: Here it’s indicated that a typical duration of an AR is 2 to 4 days, but in your study you have two separate ARS within 3 days (6 and 9 of June). Can you comment on this? It shows up as different AR events from the figures but it would be good to emphasize that these are separate events

Line 73-75: The majority of ... --> this sentence feels unlogic here as you have been talking about ARs before but in that particular section you discuss the influence on the Arctic. I would move the sentence to line 65 or remove it from the text

Line 84-89: The information provided here is already very specific and would better suit in the method or discussion section

Line 90: Shields et al. (2018) study aimed to understand

Line 146: from 1000 hPa to 300 hPa. What are the vertical steps?

Section 3.3 Air mass trajectories: For the air mass trajectories the NCEP dataset is used, which is not used for the rest of the analysis of detections of ARs, which is a bit inconsistent. Can you motivate your choice in the text, and did you analyse the performance of simulating the ARs in the NCEP dataset?

Line 180: where g is the acceleration due to the gravity

Line 225: here you explicitly mention ERA-Interim, but why don’t you compare with ERA5?

Line 297: First and second line of this section have a lot of overlap, combine them?

Line 304: ..used to study the atmospheric blocking

Line 354: After the landfall.. --> I believe here you mean the timing after the landfall while it could be interpret as location. This could be stated more clearly.

Line 378: Are you talking about the RMSE for IWV?

Line 520: Add interpretation to the sentence on low precip in ERA5

Line 660: In this study we focused on understanding

Figures & Tables

Figure 2: It would be nice to see the direction in which the AR is moving for extra insights in the event. You do show the orange arrows above 300, but could you lower it to get the direction for every plot? For the 6 June case you do not know the direction from the plot, which would give extra insights.

Figure 3: Is there a better way to visualize this data? I found the figure not very attractive.

Table 2: I wonder if Table 2 is needed in the main manuscript, as you only refer to it twice in the text and most information can be also found in Figure 5

Figure 6: end of caption --> (reference) --> still edits are needed?

Figure 9: In figure itself it should be accumulated instead of acummulated