This is a very much improved revised manuscript; in fact, in many aspects it reads as a new manuscript although the topic and the data analyzed are the same. It is indeed rewarding to review with such a response! I have only four remaining (or new) overriding issues that I think can be improved upon (below).
Three overriding concerns:
The main message: When reading the manuscript, the narrative shifts from the effects of SHI, to questioning the very existence of SHI and then back to the effects again. The introduction covers the SHI in previous studies and sets the stage for the analysis. Then with the long section with the discussion of potential measurement errors the very existence of SHI is called into question and it is concluded they do exist. This is a relief given the intro; there wouldn’t be much of a paper if the conclusion had been the opposite. However, the discussion of potential errors is then mostly forgotten in the rest of the text, which reverts back to accepting their existence; it is not even mentioned in the concluding section. This makes the section with the error analysis (Section 3) seem like a long and embedded appendix; it doesn’t fit well into the rest of the text. There’s nothing fundamentally wrong with the text seen section by section; I’m just sensitive to the narrative when looking at all the sections as part of one paper.
The error analysis (Section 3): This is worthwhile but very detailed description also with some rather trivial content. Does it have to be this long(?); it’s a third of the main text. With this degree of detail, it could have been published separately as a technical note. The authors list three potential errors. The solar heating is not considered further, leaving the wet-bulb:ing and time constant. Then, if I read this correctly, the wet-bulb:ing seems to be folded into a time-constant problem; then at the end it is not again (see final sentence). But viewing wetting this way makes things so much more complicated; it means that the system has two time constants; one related to the time it takes for the wetting to evaporate and one relating to the time constant of the instrument. In fact, there may even be three time constants; these two plus one related to the instrument housing. I recommend that either Section 3 is revisited and rewritten so that it fits the purpose of this paper, or that it is extracted from this paper and published separately. If it is kept as a part of this manuscript, the results should be reflected in the following text and especially in the summary section.
The LES study: I indicated previously that I didn’t think the LES study fitted in this manuscript. The way the revised paper comes through, I take that back. While I do feel that one can always get an LES to agree acceptably with observations if one tries hard enough (there are so many degrees of freedom to play with and usually not enough observations to constrain) the trick is to use the LES for something valuable and with the with and without SHI comparison I feel the authors succeed with only these two runs. They may both be way off to reality in some aspect, but they are then off the same way! But more work is still needed to make it fit in the paper. The text introduces just about enough information about the LES to irritates me to have to go to the Appendix to get the rest. I get to know the size of the domain, but not the resolution; for that I need to go to the Appendix. I can’t find information on how the LES is initialized and get no useful information on what the authors mean by “Lagrangian”; yet this particular information is repeated in both the text and the Appendix. The Appendix say the LES is “constrained by the soundings”, but those were done at the location of Polarstern which is the trajectory end point. So how is that compatible with a Lagrangian perspective? In short, the text describing the LES and the experimental setup needs to be revisited; I would either put all technical information in the Appendix or expand the Section in the text to get rid of the Appendix.
The SHI gap: All the results from the LES and the observations concerning the case where the SHI is disconnected from the cloud top makes sense to me, but the whole thing begs the question: Why? With the accepted hypothesis on the existence of SHIs being related to large scale advection of a deeper and moister upstream PBL that adjusts to the shallower PBL forcing over the sea ice, I don’t immediately quite see how this could happen. Where did the moisture go? In to the cloud and precipitated out, while the cloud top then proceeded to evaporate?
Minor comments:
Line 10 and elsewhere: There is considerable discussion of “latent heat flux”, but isn’t it the turbulent flux of water vapor that is important to this paper. Not the effects on or by the heat transport (energy) but the transport of mass; water vapor. So why convert it to W m-2?
Line 35: Why confine it to advection from continents? It could equally well be marine air from south of the ice margin.
Line 43: “Despite their importance …” implies an causality between knowledge and importance that isn’t necessary there. Some of the most important issues in science have turned out to be the most difficult to solve. Take “climate sensitivity” as an example.
Line 79 and elsewhere: The sonic anemometer provides a so called “sonic temperature”. This is not equivalent to the virtual temperature, although it is close enough, especially in dry environments (not necessarily low RH but low q).
Lines 79-80: Considering what comes in Section 3, this is not nearly enough discussion of these sensors. It wasn’t until the end of Section 3 I realized the housing of the T/RH sensors may be a problem.
Lines 181-187: This paragraph is actually a repetition of the previous discussion. Setting the time constant of one sensor to zero, which is already done, is consistent with setting it to any other value much shorter than the other. And setting both to zero is – in a relative sense – the same as setting both to any other single value, say for example 60 s.
Lines 213-214: How can the warming lead to a change in RH when RH is the measured variable?
Lines 219-224: See above; it’s not until here that I get the information that there might be a problem with the instrument housing.
Line 224: Confusing; reading the preceding text, I though wet-bulb:ing was THE problem, and that is what was considered above?
Figure 7: Please display the cloud base also in Figure 7c
Line 237: I disagree; while near-neutral through the PBL, it is weakly stable through the whole layer, and there is no easily distinguishable point where this increases below the inversion base.
Lines 236-239: Note that the scaling used here does not apply to the lower free troposphere, so there is no reason a priori that the profiles above the PBL top should be similar or comparable.
Line 244: Disagree again; there are clear capping temperature inversions in all the profiles. Some profiles may have embedded internal structure but that is not the same as not showing a “clear temperature inversion”.
Figures 8-10: Why is there sometimes such a large absolute difference between the sounding and the Beluga temperature profiles? Sometimes the sounding is several degrees colder that the tethered sounding; this presumably also affects the specific humidity profiles.
Lines 280-281: A difference of 20 m could well be just coincidence; the cloud top is not at one fixed height but rather goes up and down following the characteristics of the up- and downward motions of the turbulent eddies.
Section 5.3: This Section doesn’t really add much information other than as a motivation for using slant profiles instead. Therefore, either move it up as Section 5.1 and use it that way. Or drop it…
Lines 387-388: The conclusions on the distance to the PBL top rests on an assumption on a constant vertical gradient. I submit that the sections of the time series may be equally semi-constantly distant to the ABL top, but as the latter is slowly descending, the fluctuations change character from going in and out of the PBL to being entirely inside the inversion.
Lines 413-414: The simulated dq = 0.6 g kg^-1 is a factor of two smaller than the observed dq = 1.1 g kg^-1; this is hardly “close to”. |
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