Dear Drs. Randelhoff and Sundfjord,

Thanks for your resubmission. I am sorry to convey that I am not satisfied with some of your modifications. I think you did not apply the useful suggestions from the referees to the best extent possible. Please see my comments to that and some further minor comment below. I still think the manuscript is worth publishing and it could convey an important message.

From referee #2 and your response (and also referee #3 touches upon this issue, see below)
RC:
Fig. 1. Why you illustrate Atlantic Water inflow by snapshot from the model, that can be pretty far from reality (Hattermann et al., 2016 do not use data assimilation)? Why not from climatology or some reanalysis product (e.g MERCATOR OCEAN)?
AR:
> As you say yourself, it is an illustration, and it does in fact capture the real-world features and patterns that are relevant for this paper (inflow of near-surface warm and salty water). We could have hand-drawn something (this, too, “pretty far from reality”, but which would still capture the same essence), but for ease of producing the figure and because it looks nicer than what we could have assembled in a graphics editor, we used this data and plotting software that we had at hand.
> Note that this picture is confirmed by e.g. Cokelet et al. , 2008, and several other papers going back a few decades, but we believe you will agree that the situation we depict in Fig. 1 is at least qualitatively fully supported by available literature.

EDITOR: I am not satisfied with your response. First, you only show this at one location in the Barents Sea. Your response is that this is only an illustration. I think an illustration is not sufficient. If you want to show that this situation holds for a larger region (and I think you would like to make this point), you have to show that with data. And secondly, you do not show it based on real data. The referee suggests climatology or a reanalysis product; you did not do anything with this suggestion. I think this is indeed the right data to use here. Actually, my comments especially hold for Figure 2. For showing this it doesn’t suffice to use modelled data, only real data take away any doubt.

From referee #3
RC:
Other comments:
Figure 1: The illustrations are too vague and lack important geographic and hydrographic features. In the left panel, I would suggest the following changes: (1) add latitudinal circles and longitudinal lines, (2) use a better color map to illustrate bathymetry (or at least supplement a color bar for the grayscale), (3) draw general surface and bottom circulation patterns.
MC:
> We have now added the broad patterns of surface and Atlantic layer circulation patterns as far as they are relevant to our manuscript; the bottom circulation, however, is not relevant to the manuscript and we did not illustrate it.
> The following was added to the figure caption: “Arrows show selected patterns of the general circulation \citep[after][]{polyakov2012warming}. Blue arrows: Pacific-derived and other freshwater flowing along the shelf break, through the Transpolar Drift and in the Beaufort Gyre. Red arrows: Atlantic-derived water entering the Arctic Ocean through Fram Strait and the Barents Sea, flowing along the shelf break, submerging north of the Barents Sea and recirculating along the shelf break through the Arctic Ocean. Other major currents are not indicated here as they are of minor importance to this paper.”
> We have also added a colorbar and the location of the transect shown later in the manuscript.
AR:
> We think longitude/latitude coordinates do not contribute significantly in this context, they would rather clutter the figure, which is why we refrain from adding them. If the reviewer has particular reasons for why they should be included we will be happy to reconsider.

EDITOR: This is again about Figure 1. As referee #1, this referee is not satisfied with Fig 1, and I agree with that. The quality of this Figure is just not high enough. Actually, it is very much distracting from the message. The commentary discusses features along the shelf break, then those shelf breaks should be clearly visible with all of their details. The Figure just does not make a good impression. Please why don’t you just provide a high-quality figure with latitude-longitude (of course, every map needs lat-long, no discussion at all). You do not provide a deep data analysis, which is ok as this commentary is not meant to do that, but then at least you can give care to the production of insightful figures, which also enhance the message.

Comment by referee #3 and your response:
RC:
Figure 2: Please mark corresponding transect in Fig 1 left panel. Why not plotting temperature, salinity and density fields in this transect all together so that readers can better interpret Atlantic and Arctic water masses, vertical mixing, thermal or haline stratification? How many CTD profiles were casted along this transect? Please mark the CTD cast locations. What were the wind conditions during this transect sampling? I think wind diagnosis would be critical in answering whether or not vertical mixing was caused by upwelling.
AR:
> Fig. 2 (Fig 2, right panel in revised version) is an illustration of what the density field looks like, generically, without consideration of special wind situations. Discussing the specifics of this transect would only distract from the general points we are trying to make: That a) these kinds of cross-slope hydrographical snapshot transects do not tell us anything about whether upwelling was happening or not (and so whether we plotted temperature and salinity should not change the reader's judgement anyway), and b) that there is no physical reason to expect a dominant signal. Fig. 2, left panel (previously Fig 1 right panel), illustrates the geographical salinity and temperature patterns, thus indicates water masses present at the surface.
MC:
> We added a sentence to the figure caption to make clear that this is “just” a representative illustration.
> The revised figure also includes station markers now and for completeness' sake bottom bathymetry from IBCAO3 plotted into the transect.

EDITOR: I agree with the comments by the referee and think the authors wipe away the valid arguments of the referee too easily. For the reader it is certainly quite useful to see temperature, salinity and density. The authors argue that it should not change the reader’s judgement anyway, but please leave that to the reader. For the authors it suffices to show everything that might be important and relevant, explain it and leave the judgment to the reader indeed. Do not care about distraction from the general points you are trying to make: It is especially distracting if obvious factors are left out. So, what about the wind patterns and their analysis? Seems to be a factor when talking about upwelling. At a later stage in the manuscript, the authors do indeed mention the wind patterns as a factor for upwelling, so why not here?

From referee #3 and response:
RC:
In section “Summertime upwelling north of Svalbard?”, the argument is unconvincing without showing results from mooring or ship-based hydrographic measurements. Personal communication is not sufficient.
AR:
> The argument rests entirely on general physical arguments. The personal communication is just an illustration.
MC:
> To get our point better across in the manuscript, we inserted “As we have seen, consideration of general physical and geographical patterns alone such as boundary layer physics and wind patterns already leads us to conclude that upwelling should not be expected to feature very prominently on the Barents side of the Arctic. This is not to say that upwelling events cannot ever happen (and indeed, in a system as complex as the Earth, it would be surprising if they would never happen), but no known physical mechanism would suggest a magnitude, frequency or importance similar to what has been found in the Pacific sector. To illustrate our point, let us just mention some upcoming work by A. Renner and collaborators [...]”

EDITOR: It would be more convincing if the mentioned general physical and geographical patterns were explained so that the reader would understand. Actually, this is exactly what such a review-like paper should convey.

The abstract does not reflect the contents of the manuscript. It is all about the physical environment and upwelling, but there is hardly any word about what this means to primary productivity. Laying the connection between those two is after all the main goal of the paper. Please restructure the abstract.

P1, L18 Many regions, but only one reference. Please give some more.
P1, L22 What is ibid here? It is definitely clearer to give the correct citation here.
P2, L1 I think this is the right place to give at least several references, and possibly add: “and more below”)

P2, L2 “As the ice cover recedes from the shelves into the basin” It is not clear what time scale is valid here, seasonal, annual, decadal? Maybe rephrase to make this clear.
P2, L3 “primary production is projected to keep increasing (Arrigo and van Dijken, 2015):” Some reasons for higher production are mentioned. There are also factors that may cause less production, e.g. enhanced stratification. Since it is not clear at all whether the production would increase, I think the entire story should be told here. Moreover, only one study with a positive response is cited here. Since the increase of primary production is a central point in your argument, you need to refer to more studies that may predict higher production. If at all known, also studies that project no increase in production should be cited.

P2, L9 “and argued that decreased ice concentrations will enhance upwelling in the area” For what reason did they argue that? That should be important info for the reader here.
Figure 1 caption L2: delete: black (word is not necessary, and giving the wrong associations)

P4, L2 delete: Not surprisingly (not appropriate here)
P4, L3 in the Arctic Ocean (instead of in the world ocean)?

Figure 2 In such a figure, latitude and longitude is of much help to the reader and it is standard indeed. For example, it would be visible where the section is situated. The cruise data presented in the second panel need a reference.
I agree with referees # 2 and # 3 that it would be more correct to take real data instead of modelled data. Is there any evidence that the larger-scale situation is exactly in agreement with this model? In a situation like this, real data, if available, is always preferred above modelled data.

P5, L4-5 “In contrast, the Beaufort sea is strongly stratified throughout the year; there, winter upwelling can be an important factor contributing to the pre-bloom nutrient pool” Earlier it was stated (and the data from Codispoti et al show it as well) that the nutrient concentration, even in winter are very low, i.e. not much productivity there, and so upwelling does not enhance productivity in reality.

P5, L22 “This is because water that already is at the surface will not profit from further upwelling” This is not unequivocal. The characteristics of this water at the surface should at least be added.

P5, L28 delete: as we will see later

Figure 3: There is also a comments by referee #3 about this.
What surprises me is the piece of text: “based on ERA-INTERIM data”. Does this mean that those data, and all of those data, were used? But then, the reference is from 2011, while the data should be for 1987-2017?
In the caption of Figure 3 “A daily windspeed was considered “potentially upwelling-favourable” if its (approximately easterly) along-shelf component exceeded 3 m s-1 for at least 3 consecutive days. (3 m s-1 is rather low a wind speed and makes for a generous criterion in this regard; there is no universally accepted measure.)” First, I wonder where the criterion comes from. There must be some literature about such issues, I think. And then second, if the criterion is not generally accepted, as you write, this strongly reduces the validity of your argument. As to the few appropriate data, could it be that the model data and reanalysis data are biased with regard to along-shelf winds?

P7, L1-2 “But it should be kept in mind that ice cover by itself is not a show stopper for wind driven upwelling (or for Ekman pumping for that sake)” The connection to the previous sentence could be guessed at most. I think the steps you are making are too big. Please rephrase clearly what you intend to convey here.

With best wishes
Mario Hoppema