Dear Authors,

thankyou for your revised manuscript “Diode laser based gas analyzer for the simultaneous measurement of CO2 and HF in volcanic plumes”. I’m pleased to be able to say that it is conditionally accepted for publication in AMT, but first it needs a little editorial work by the authors.

Some of the responses to the reviewers comments are somewhat unclear (in the revised ms.; in the detailed explanation your intent is clearer).

Please see the list below.
regards
Murray Hamilton
(Assoc. Ed.)

First, reviewer #1 was correct that you should not have used the word “alternatively” in this context, but their suggestion of “alternatingly” is not actually a word in the English dictionary! The correct word is “alternately”.

In your response to the reviewer’s comment on various commercial instruments and their URL’s, the overrun of the URL on page 3, line 20 means information needed to actually use the URL is missing.
In any case it is better not to give the full URL for products as its lifetime is limited due to manufacturers frequent reorganisation of their websites. It is better to limit the URL to just www.company.com since that part of the URL is much more long lived, and it is usually easy to find the product from the top level. Also the text “URL=“ is superfluous.

On page 4,line 18, the notion that the fibre coupler is a “standard one” is a bit unclear. This statement could be omitted and the rest of the sentence merged with the preceding sentence.

Please have a look at page 3, lines 10-15. This reads awkwardly - the passage seems to restart at the second use of the word “several”, though in fact this is not the case.

It is bad form to start a sentence with a symbol - see page 1, line 24 and elsewhere. Page 3, line 17 is how it should be done.

On page 6, line 3, you send a beam *through* a cell rather than across.

On page 6, line 23 and following, it appears as if some paragraphs may have been meant to be joined. Please be consistent throughout with the line indenting of paragraphs, and whether you have a blank line between paragraphs.

On page 7 line 10, you should omit the word two - it creates confusion as the two are the main and reference (I think). If in fact you mean there are two main signals then further explanation is needed.

Page 8, line 4; the end of the sentence is tautological

Page 8, line 13; “Knowing”, not “Known”

Page 10, line 11; the commonly accepted symbol for standard deviation is sigma, not 2*sigma.

Page 12, line 8; The sentence starting “Moreover …” is unclear in view of what is written later. Is this the value of the correlation after a 16 s time shift has been applied to one of the data series?

Page 13, line 4; Saying “Three optical fringes … are included” is ambiguous. Do you actually mean three fringes, or three fringe patterns each with different fringe spacing? I would actually expect the latter, and in the former case forcing that number to be an integer is very artificial.

page 14, line 2; it’s a 3 minute interval, even though it lasts 3 minutes!

Page 15, line 6; Why is this in the plural?

Page 16, line 3; “The air can be taken a few meters apart …” is actually meaningless and needs to be rephrased

Page 16, line 17; replace “one” with “absorption resonance”.