I am happy that the scientific issues raised by the referees have been satisfactorily addressed, however the text needs some grammatical tidying up before final publication. Here are some (no exhaustive) suggestions.

The abstract needs a really good proof read. Examples might include:
(1) Mixed tenses.
(2) line 10: spurious “a” before numerical.
(3) line 13: missing “t” from constraint
(4) line 14: capitalise Lagrangian
(5) line 15: replace “of regional configuration of MITgcm of” with “regional MITgcm configurations”
(6) last sentence: replace “can make modest contribute” with “can make a modest contribution”
(7) last sentence: insert “the” after “drive”


Page 2, line 17: replace “on” with “one”
Page 2, replace “k” with “gas exchange velocity” as it is not defined ’til later
Page 2, equation 1 and variables in surrounding text (here and throughout): Make sure the fonts are consistent.
Page 2, lines 24 and 25: I presume “m d-1“ is metres per day. Superscript the “-1” to make sure it gets typeset properly.
Page 2, lines 30-32. This sentence doesn’t make grammatical sense.
Page 3, line 1: replace “.” with “,” after the word stratification with “,”
Page 3, line 11: replace “history which” with “history in which the”
Page 3, line 12: replace “through water” with “through a region”. The water column is the water!
Page 3, line 24: replace “suit” with “suite”
Page 3, line 29: insert “the” before “Arctic” replace “Models” with “Model”
Page 3, line 30: insert “the” before “main” and remove spurious “s” at end of line
Page 4, line 3: remove the word “output”
Page 4, line 9: remove “’s” from “ECCO’s”
Page 4, line 14: ECMWF is European and so it is “Centre” not “Center”. Also remove the capital from “The” as it is not part of the name.
Page 4, line 30: I think you should replace “has” by “have” in both cases
Page 5, first line: define ITP-V
Page 5, line 3: replace “at the mixed layer” with “in the mixed layer”
Page 5, line 14: put “Figure 3” in brackets.
Page 5, line 20: put “Figure 3” in brackets.
Page 5, line 22: “Fig 4” should be “Fig 3”
Page 5, line 20: put “Figure 3” in brackets, twice.
Page 6, equation 2: define the quantities in this equation, alternatively give a reference as this is very standard.
Page 6, line 14: replace “manifest” with “manifests”
Page 6, line 23: fix “sam e”
Page 7, line 6: I assume the word “occurs” should be inserted between “which” and “overs” - the later which should be replace by “over”
Page 7, line 7: T and S not defined. given they are only used twice just use the words in both places.
Page 7, line 15: The reference tool seems to have gone awry here.
Page 7, line 25: is the “PW” really meant to be PSW. If not define.
Page 8, line 5: Remove the second “zone”.
Page 8, line 8: reword
Page 8, line 10: insert “the” before “volume”
Page 8, line 11: remove the first “late”
Page 8, line 13: replace “decrease” with “decreases”
Page 8, line 14: replace “exposed” with “exposes”
Page 8, line 29: remove the brackets around “Figure 7”
Page 8, line 32: reword
Page 9, line 17: replace “lead” with “leads”
Page 9, line 26: replace “suit” with “suite”
Page 9, line 27: inset “a” before the word “variety”
Page 10, line 14: end sentence “at a 6-hourly frequency”
Page 10, lines14 and 15: The references at the start of the sentence shouldn’t be in brackets.
Page 10, lines 17 and 18: Use either Jra55 or JRA55 consistently. Also I note JRA25 was used earlier is this a mistake. If not provide a reference for JRA55 and NCEP.
Page 10, line 29: replace “on” with “at”
Page 10, line 30: I presume equation 2 is being referred to here. In which case the N should be n and also defined (is it days, weeks, months, years.
Page 10, line 31: SI has not been used up to this point so should be defined or given that it is only used a few times spelt out. Also replace “has” with “have”.
Page 10, line 32: replace “speed” with “speeds”.
Page 11, line 9: What is the “(0.27)” I can’t see this number elsewhere.
Page 11, line 27: insert “the” before “current”
Page 11, line 28: replace “models” with “model”
Page 11, line 31: remove “a”
Page 11, line 32: remove “a”
Page 12, line 14: replace “resolution” with “resolutions”
Page 12, line 19: should “brine rejection scheme” be replaced by “salt plume parameterisation” as “brine rejection scheme” hasn’t been mentioned up to this point.
Page 12, line 21: replace “product that is” with “products that are”
Page 12, line 22: replace “product” with “products”
Page 12, line 25: replace “evident” with “evidenced”
Page 12, line 28: replace “on how” with “of how”
Page 12, line 32: do you mean “high frequency” rather than “low frequency” (based on discussion that in the manuscript that it is the high frequencies missing from the model forcing).
Page 12, line 34: replace “include” with “includes”. In fact you might want to tighten up the last couple of sentences so the ending is clear/.
Page 14: Sort out the Perovich reference.
Page 20, caption: Replace with “A graphic illustration of two possible back trajectories for a single sampling station.”
Page 22, caption: For (A) replace “averaged” with “average”. You also should say what the quantity is! Replace “ground” with “land”.For (B) say what the quantity is being represented. For (C) while I can see the orange line, it appears closer to the 80% cover and I can’t see a red line at all. For (D) the caption should state that the blue dots are satellite data and the red line is model A1, particularly as the legend os rather small.
Page 25, caption should ITP-V really be ITP as nowhere else is ITP-V mentioned when referring to this figure? Units are missing after 1022.5
Page 26: The caption doesn’t fully describe the figure
Page 28: The caption should give the time averaging period for the data. The text says that the observations are daily averaged. The model output appears to be averaged on a much longer time scale (it is far smoother than any comparable model output that I’ve examined). If this is the case the correlations aren’t really fair.