Comment on acp-2021-609

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. The complete information with the dates of the ACLOUD campaign was removed from the abstract. We included information about the year of the events since it was not included in the previous version of the manuscript. The updated version of these sentences is shown below: objective of this was to build knowledge from detailed AR case studies, with the purpose to perform long-term analysis. Thus, we adapted a regional AR detection algorithm to the Arctic and analysed how well does it identify ARs; used different datasets (observational, reanalyses and model) and identified the most suitable dataset; and analysed the evolution of the ARs and their impacts in terms of precipitation.

Can you indicate the research question/objective more clearly in the abstract? And as well in the introduction?
The authors thank the suggestion from the referee. The research question/objectives of the manuscript were explained with more detail by including the following sentence to the Abstract: "The objective of this manuscript was to build knowledge from detailed AR case studies, with the purpose to perform long-term analysis. Thus, we adapted a regional AR detection algorithm to the Arctic and analysed how well does it identify ARs; used different datasets (observational, reanalyses and model) and identified the most suitable dataset; and analysed the evolution of the ARs and their impacts in terms of precipitation." The objectives of the manuscript were already included in the Introduction, in the last paragraph of this section: "Further, we apply these various observational and modelling products for investigating the ARs development and evolution, their role in the poleward moisture transport (reaching and affecting Svalbard and Greenland), and associated precipitation characteristics. Another purpose of this study is to adapt the AR tracking algorithm by Gorodetskaya et al. (2020), developed originally for Antarctica, to the Arctic region, to evaluate how well does it identify ARs and to identify the most suitable reanalysis dataset to analyse this type of events. Building on this detailed case studies analysis, it will be possible to extend this work to longer time periods from the recent past (using reanalyses) and into the future." Line 21-25; is all this information needed in the abstract or can you reduce the text here?
The authors tried to shorten these sentences, by removing specific information about the spatial ("ranging from 0.25 to 1.25 degree") and temporal resolution ("ranging from 1 hour to 6 hours"). Also, the sentence "Despite being consecutive, these events showed different synoptic evolution and precipitation characteristics" was removed, since the following sentences in the manuscript already mention the differences in the synoptic conditions and precipitation amounts and phase.
The upgraded version of these sentences is shown below: "Results show that the tracking algorithms detected the events differently partly due to differences in spatial and temporal resolution, and in the criteria used in the tracking algorithms." Line 33: there was an increase of values with height. This 'of values' is not really clear. Can you improve this sentence?
The authors changed and shortened the sentence, in order to be more readable. The updated version is shown below: "There was an increase of wind speed with height during the first and last events, while during the second event there were no major changes in the wind speed." Line 35: ..during spring and beginning of summer ..
The authors thank the referee. The new version of the manuscript includes this correction.

Minor comments
Line 53: reasons Thank you for the comment. In our opinion the sentence is correct since "Gimeno et al.
(2019) reason in their review (…)" is a study performed by multiple authors, and that is why reason is in plural form.
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 The information about the typical duration is not directly related with ARs. The study that mentions the 2 to 4 days duration is about moisture intrusions (Woods et al., 2013), which are not exactly the same phenomena as an AR.
In our study, we did not mention the typical duration of ARs, because it depends on the region, and there are not many studies about ARs in the Arctic. In the case of these consecutive ARs detected in a 3-day period (June 6 and 9), they were short duration events. Based on Figure 5, one can notice that the IWV and/or IVT peaks had a short duration, associated with these short events. Additionally, these two events were detected by different algorithms: the 6 June pAR was identified by Gorodetskaya et al. 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 The authors decided to remove the sentence. Also, the reference Zhu and Newell (1998), was removed from the manuscript since it only was referenced in this sentence.
Line 84-89: The information provided here is already very specific and would better suit in the method or discussion section The authors understand that the information provided in lines 84-89 is too technical to be included in the Introduction (Section 1). Thus, we thank the suggestion from the referee, and moved the paragraph to the beginning of Section 3.2, where we explain in detail the algorithms used to detect atmospheric rivers. This paragraph is suitable to give a short introduction about the topic of AR tracking algorithms.

Line 90: Shields et al. (2018) study aimed to understand
The authors removed the adverb "Furthermore" from the beginning of the paragraph. The following paragraph was updated in the new version of the manuscript:

"Shields et al. (2018) study aimed to understand…"
However, the authors are not sure if this was the suggestion made by the referee.
Line 146: from 1000 hPa to 300 hPa. What are the vertical steps?
The vertical resolution of the reanalyses depends on the dataset. For ERA-Interim, ERA5, CFSv2 and JRA-55, we downloaded 20 pressure levels. From 1000 to 750 hPa the vertical steps were 25 hPa and from 700 to 300 hPa the vertical steps were 50 hPa. In the case of MERRA-2, we downloaded 21 pressure levels. From 1000 to 700 hPa the vertical steps were 25 hPa, while from 650 to 300 hPa, the vertical steps were 50 hPa.
Some information about the number of pressure levels and vertical steps was included in the updated version of the manuscript: "To detect the ARs, specific humidity, temperature and meridional and zonal components of the wind were acquired from 1000 hPa to 300 hPa. Except for MERRA-2, all reanalyses were downloaded from 20 pressure levels, with vertical steps of 25 hPa, from 1000 to 750 hPa, and vertical steps of 50 hPa onwards. In the case of MERRA-2, the variables were downloaded for 21 pressure levels, from 1000 to 700 hPa, with vertical steps of 25 hPa, and from 650 hPa onwards, with vertical steps of 50 hPa." 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?
The authors thank the comment from the referee. Although the choice of NCEP dataset might seem a bit inconsistent, the reason why we chose this dataset is because, concerning the available datasets, this was the most suitable for our study. In the HYSPLIT online platform (https://www.ready.noaa.gov/hypub-bin/trajasrc.pl) the datasets available for the archive trajectory model are the following: Several datasets do not cover the period analysed in our study (May -June 2017), such as 2, 5, 10 and 11. At the same time, some datasets are focused on some regions, such as the U.S (4, 6, 7, 9 and 13) or North America (8). The datasets that cover the period and location of this study are 1, 3 and 12. Both datasets 1 and 3 are from the NCEP Global Data Assimilation System, and dataset 12 is from the NCEP/NCAR Reanalysis. We chose the dataset 3 (GDAS -0.5 degree), since datasets 1 and 12 have both lower horizontal resolutions, respectively 1 degree and 2.5 degree.
The performance of NCEP to simulate ARs was not analysed in this study. All the datasets used to identify ARs were shown in the manuscript.
A short explanation about the choice of this dataset was included in the updated version of the manuscript: "For this study we used NCEP's Global Data Assimilation System (GDAS) model, with a horizontal resolution of 0.5 degree. Amongst the datasets available in the online platform, this was the most suitable to our study, due to its finer spatial resolution." 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. The authors thank the comment from the referee. An effort was done to make the figure more attractive. The yellow colour, previously representing CFSv2, was changed to blue to be more visible. Furthermore, we plotted each time step closer, to be easier to understand if there was an increase/decrease of the pAR/AR area during the evolution of each event. 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 The authors thank the comment from the referee. Indeed Table 2 is only referred twice in the manuscript. Since this table has important information, that is more easily read in the table that in Figure 5, we moved Table 2 to the Supplementary Material, and in the new version of the manuscript it is named Table S2. The caption from Figure 6 is already completed. The "(reference)" in the end of the caption "… and Figure S9 shows the differences between each reanalysis and model and the radiosondes (reference)" is meant to explain that in Figure S9 the radiosondes are used as reference for the differences. Thus, all the results shown were calculated using the following formulation:  The authors thank the correction. The colorbar title in Figure 9 was corrected. Also, the titles in Figures 8, S11, S12 and S13 were corrected.

Figures & Tables
The figures are shown below: