Dear authors,

thank you for taking the two reviewers suggestions into account and revising the manuscript accordingly. There are a few points desribed below where I would like you to make some further amendments. Should be quite straight-forward and hopefully not take too long.

Best regards,
Marc von Hobe


Further suggested revisions:
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In the last paragraph of Section5, the sentence
"The overestimation of low amounts can be explained because the a priori SO2 amount
used by IASI retrieval is 0.5DU and in case of no information content from the measurments (as happen when there is no detectable SO2 ) the output of an optimal estimation retreival is the retreival is the a priori value."
is grammatically incorrect and I'm not exactly sure what you want to say. Please revise!

With respect to the estimation of tropopause height, if I understand your response to reviewer 1 and the paragraph in Section 6 correctly, you determine the WMO TP height in terms of pressure altitude and convert that to geometric height using the hydrostatic equation? I suggest to use the local geopotential height to convert pressure altitude to geometric altitude. Simple use of the hydrostatic equation can lead to errors of up to 2 km, espectially in the tropics.

I find figure 2 in your author response relating plume height to VEI extremely useful and interesting, and recommend including it in the paper. Please add a reference for the source of the VEI values, preferably a commone one (e.g. Smithonian global volcanism programme). Ideally, you would even add a note that the VEI data are not always unambiguous, and that different values are present in the literature. This is particularly important for your only VEI 5 volcano, Puhehue, for which values of 4 and 3 are also found
(e.g. VEI 3 in Dzierma and Wehrmann, And. Geol., 39, 380–393, 2012).

Dear authors,

thanks for making the additional amendments.

I think the work has evolved into a very nice and useful paper, which I hereby accept for publication in ACP.

Best regards,
Marc von Hobe