Dear Authors
Thank-you for your revised submission. The reviewers are agreed that this is a useful study but generally wanted more novel content. The “Technical Note” guidelines refer to “new developments, significant advances, and novel aspects . .” and do not themselves remove the desire for novel content. The comments below include instances where I think you should do more to respond to the reviewer comments and in many cases include something of your response in the revised manuscript. Two reviewers called for “major revisions” and I expect to send it back to one or two. They could be annoyed if their comments are not reflected in the revision; moreover, eventual readers would benefit from a self-contained paper without being expected to read the discussion comments in parallel.
In view of all the above I think it best if you would please address the comments below before I send it again to referees.
[NB the system calls this process "Reconsider after major revisions" but I don't think what I am asking is "major". Eventually that judgement is also for Referees.]
Yours sincerely
John Huthnance

Lines 45-46. I think this is one place to say clearly how this work advances knowledge and is novel. The presents statements here are rather “low key”.
Line 47. It is not clear to me why the mid-latitude example is “general” – omit in view of the Referee comments on this?
Section 2.1, penultimate paragraph. Probably not your response figure but some discussion of error sources and magnitude in emissivity estimates should be here in response to Referee 3.
End of section 2.1. To answer Referee 2 about Rosenkranz (2017) in the text you could explicitly mention its competence for oxygen at L-band and citation of other references forming the state of the art.
Line 78. “hydrometeor” –> “hydrometeorological”?
Equation (1) et seq. Please include something of your response to Referee 1, probably citing Matzler (2005) which should be added to the references.
Equation (2) et seq. similarly, i.e. please include something of your response to Referee 1.
Similarly again, after equation (3) you could refer the reader to figure 4 for plots with un-normalised sensitivities, and in the figure 4 caption something of your response to Referee 1 about figure 4.
Lines 106-107. You could refer here to figure 4 for the Arctic (re. Referees 2 and 3 comments on figure 2).
Line 111 end: “. . frequency” (no “,” and more usual English)
Figure 2, Referee 2 subsequent comment about variations due to surface and atmospheric conditions; in figure 2 caption you could refer to figure 3 for these variations.
Lines 166-167. You could make it clearer that taking into account the atmosphere, and considering different geophysical conditions, are advances; you did not just “reproduce” Wilheit (1979).
Lines 168-171. These read as for the Introduction although you do want a summary merged in to your confirmation that these choices do indeed serve the purpose.
The last paragraph should incorporate your response to Referee 1 that multi-channel analysis has been presented in Kilic et al., 2018. This is not clear as presently written.

Dear Authors
Thank-you for your re-revised submission. Two reviewers have seen it again and agree to publication on the basis of this being a useful study albeit not really novel. They are not asking for further changes. Nor am I.
You should please enter your final version to the Copernicus Editorial system for publication (no more intervention by myself). There will be copy-editing. Please check that this keeps the meaning you intend.
Thank-you for publishing in Ocean Science.
Yours sincerely
John Huthnance