Dear Dr. Bianchini,

based on the evaluation of two reviewers, your revised paper is almost ready for publication.

Please address the remaining comments of reviewer #1:

P3,L9: replace “problematics” with “challenges”
Fig 1 caption: left and right panels, not top and bottom
P5,L11: replace “do” with “does”
P7,L24: replace “it is shown the result of this analysis for two different lines” with “the results for two different lines are shown”
P11,L1: “provided an Ethernet connection”
P12,L3: “expected atmospheric radiance signal”
P12,L4: remove “with respect to the instrument accuracy”
P12,L17: “continuously performed (or when very dry conditions exist which is frequently at Concordia) during a multi-year”
Fig 8: the gray line showing the difference is very hard to see; please increase the context
P13,L6: “of the system; however, this is at the cost of a lower absolute stability of the spectral calibration reference.”
Pg 14,L3: replace “has not to be” with “does not need to be”
P15,L6: replace “performances” with “performance”
P18,L1: replace “evidence” with either “importance” or “note”
Pg18,L10 (and Fig 13): the downwelling radiance spectrum in the right-hand panel is not from a tropical atmosphere. The tropics have a large PWV and thus there will be significant downwelling radiance in the 800-1000 cm-1 spectral region (not ~zero as shown here). My guess is that the wrong spectrum was accidentally plotted here
Pg 18,last line: “a software package has”
Pg19,L3: “The software retrieved temperature and water vapor content profiles”
Eq1: no “+” in the equation
Pg 19,L11: “where y and x are the vector” (they were accidentally reversed in the paper)
Pg 19,L12: “VCM” has not been defined in this paper
Pg20,L10: “Figure 13 left panel”
Pg20,L21: “data product. The accuracy in the”
Fig 15 caption: “in Figure 13 left panel”
Fig 16: Question: is the low level warm temperatures in the right panel (lowest few m) actually the temperature inside the instrument and/or chimney? If so, this should be noted in the caption or text.
Pg21,L4: “be retrieved. For example, nitrous oxide is obtained…”
Pg21,L6: “In Figurew 17 bottom panel a time series of the retrieved N2O obtained …period is shown.”
Pg21,L9: “…is added to the retrieval range. However, the main methane absorption feature overlaps with the absorption bands of the Mylar…” (i.e., remove the “(differently from…main absorption features”
Fig 17 caption: “OMI measurements over the Dome C region are also shown.”
Pg 22,L9: is there a reference for the OMI data you are using?
Pg22,L16: “analysis process provides a valuable tool”
Pg22,L17: “Figure 18 shows the result…”
P22,L19: “without any significant maintanence.”
P23,L20: “relevant cloud-free atmosphere processes, which is the reference case in this work.”
P24,L13: The extended-range AERI at the ARM NSA site, which has been operating there since 1999, is a similar instrument to the REFIR-PAD in that it measures downwelling spectral radiance in the mid and (part of the) far-IR (although not as deeply into the far-IR). So the statement that “no similar instruments are operating continuously in polar regions” is mis-leading, and should either be removed or reworded.

Thank you and best regards
Lars Hoffmann

Dear Dr. Bianchini,

it is my pleasure to accept your paper for publication in AMT. Congratulations!

Best regards
Lars Hoffmann