|Review #2 of Vilibic et al, OSD :|
This is the second review of the manuscript « Dense water formation in the coastal northeastern Adriatic Sea: the NAdEx 2015 experiment » by Vilibic et al. The authors have provided a comprehensive response to the previous comments which is highly appreciated. They have convincingly responded to a majority of the major remarks and to most of the minor ones (although new minor concerns arise), which is a significant step forward toward the publication of their work. However, several major issues previously arosen still remain, which either fragilize some of the authors’ conclusions or complexify the reading. I therefore recommend a major revision of the manuscript.
The following major concerns still remain:
M1 Although the authors disagreed with me on the too large number of Figures, I believe this remark is even truer now that the manuscript reaches 20 Figures. Some of them provide repetitive informations and others are too raw to support the authors’ claims, fragilizing them. The authors should seek to be more synthetic and to add a few (simple) diagnostics to some Figures to be more convincing. In particular:
- I still believe Figures 11 and 12 repeat already-existing informations and the added value of showing statistical distributions is very low as it is presented. Also, as mentioned in former remark m14 (which has not been addressed), I think displaying relative differences (Fig.11c,d and Fig.12d,e,f) is irrelevant: especially for salinity, it gives the misleading impression that the bias is low and it makes it hard to read the actual salinity bias. As mentioned in the previous m14, absolute differences would be easier to read and interpret. For the q-q plots (Fig.11a,b and Fig.12a,b,c), the dashed-dotted line is still not labelled, please explain how it is obtained.
- As mentioned in the previous review, model-obs Figures could easily be merged with obs-only Figures, which would make the reading much simpler. The authors have already successfully done it for Figure 6, they could do the same by removing Figures 9 and 10 and putting them aside their observational counterparts.
- As already mentioned before, Figure 15 is not insightful as it is now and could also be removed. The SI difference doesn’t read well and plotting directly both time differences would have been easier, and most of the domain already has a very low (<0.05m²/s²) stratification before the Bora events occur. Also, diaplaying the MLD would be very insightful (see comment M3).
- The new Table 2 is too instantaneous to be insightful and could also be removed. Instead, the intense transports during Bora events could be compared in the text to the winter mean transport (e.g. on average during the 6 Bora events, the T, S and volume transports are respectively X times, Y times and Z times larger than their winter mean value). Also, mass and volume transports are almost identical so that the mass transport could be removed from Table 1.
- The very large number of geographic locations makes the reading very confusing. In particular, the following locations should appear in Figure 1: Istria, Sedmovrace, Senj, Kvarneric (confusion between A4, T4 and Kvarneric transect).
M3 Although the authors have put forward more explicitely both hypotheses of a DWF occurring locally or dense waters from the open Adriatic shelf, I still find the conclusions confusing, including those stated in the abstract. In addition, as in coastal areas DWF occurs exclusively when the mixed layer reaches the bottom of the water column, the lack of any mixed layer computation is still a major drawback of the paper.
- Regarding the first point, here is the conclusion I have reached, which is clearly stated nowhere in the paper : « Observations at transect T4 and station A9 show the incoming of dense water from the open shelf, and current profiles only show marginal outward transport of dense water from the NADEX area to the open shelf. They support balanced inward-outward dense water exchanges or even a dominating inward transport. However, modelling results show the domination of outward dense water transport, strongly supporting the hypothesis that the NADEX area is a source of dense waters for the open Adriatic. » Please re-formulate more clearly the respective contributions of the local formation, outward and inward transport in the NADEX area to the DWF phenomenon, in particular in the abstract, the conclusion and section 4 (p.9, L.4-25).
- Regarding the lack of any mixed layer computation: I believe that comments of Figure 13 are not convincing without an MLD being displayed (see also comments m9 and m11), and the color range change obviously didn’t fix the issue (it is still impossible to read with the eye a 0.01kg/m³ density variation). I also believe (former M8) that Figure 15 should be removed if no mixed layer is displayed (eg: relevant contours). Figure 15 would be insightful if the IS time difference map was displayed together with a relevant MLD contour (e.g. 50m depth) before and after the Bora event, so that the reader can objectively identify the regions of DWF created by the Bora event.
M11 (new) The authors claim in their response to have addressed their general question 4 (What are the associated mesoscale and frontal processes associated?), which I believe is not the case: no actual mesoscale or frontal process has been studied, they have just identified a front. As questions 1 to 3 are enough, I believe question 4 should be removed.
Here is a list of the new minor concern :
m1 The authors have identified an interesting bottom hydrological trend in observations which is the main signature of DWF: they should evaluate it in the model.
m2 p.6, L.15 Compare year 2015 to the 10-year average rather than to specific years, because the fact that it is lower than 2012 and higher than 2014 doesn’t prove that year 2015 was average.
m3 p.7 L.27 How do you know that this incoming occurred dominantly through T4 connecting passage ?
m4 p.9, L.4-5 Question 2 is not answered to in the whole manuscript (see comment M3).
m5 p.8, L.28 Fig.5 not Fig6.
m6 p.9, L.5 Fig.6 not Fig7. The orientation of all channel cross-sections would help a lot to interpret Fig.6 as each section has a different orientation (e.g. just display for instance a horizontal line on top of the current measurements if the section is East-West).
m7 p.10, L.15-16 Positive bias, not negative.
m8 p.11, L.11-21 The model evaluation is too qualitative, be more quantitative (e.g. bias in the module and in the angle). For now it is not convincing that the model performs overall well.
m9 p.11, L30 The water column was not homogeneous all the time from December to early April. Only displaying the MLD in Fig.13 would determine when it occurred (when the MLD reached the bottom). For instance, it is clear that DWF was intermittent in early January and in March.
m10 p.12 L.3 Also (maybe mostly) the surface radiative forcing restratifies the water column.
m11 p.12, L.3-5 I don’t agree on the comparison between G1 and G2: the water column looks much more homogeneous throughout the winter in G2 than G1. Once again, displaying the MLD would determine if it is the case or not.
m12 p.13 L.14 Why do you expect wind-driven dynamics to induce an energy loss?
m13 p.14 In the formula, rename U vector as Uout for instance to specify that it is only the outward velocity.
m14 p.14 L.13-25 There are a series of English and typing mistakes, please correct them.
m15 Use the same range of values between Fig.17 and 19.
m16 p.17 paragraph 1 Also, the lateral boundary conditions for momentum impact highly the level of kinetic energy close to the coastline. Do you have free-slip conditions? If not, this would be a means of improving the modelled velocities in the NADEX area.
m17 p.17 L.15 Don’t talk about one-way coupling: it is just a forced atmospheric simulation.
m18 A schematic scheme of the main phenomena evidenced in this field campaign would help the reader to have a general overview of the main results of the study.