Dear Georgina and colleagues,

congratulations, your paper is almost ready for publication. I have only two technical issues:
1. I am not sure if a reference is possible in the abstract without resolving it in the abstract. Possibly it might be necessary to add the related bibliographic data in parentheses instead of referring to the references section of the paper.
2. The term "retrieval error" in line 2 of the Discussion is somewhat ambiguous. In Clive Rodgers' terminology the retrieval error is retrieval noise AND smoothing error, while others use this term in a more generic sense. I suggest to remove the ambiguity by using a more specific wording here.

By the way, MIPAS has also been used to measure volcanic SO2 (Hoepfner et al.
Sulfur dioxide (SO2) from MIPAS in the upper troposphere and lower stratosphere 2002–2012
Atmos. Chem. Phys., 15, 7017-7037, 2015.

Regards,
Thomas