Dear Authors,

Thank you for taking care to carefully revise your manuscript and address the concerns of the referees. Both referees agree that the revised manuscript is suitable for publication once a few very minor technical corrections listed below have been addressed.

I look forward to receiving your manuscript and to the publication of your paper.

Regards

Dominick Spracklen


Technical Corrections

Please check figure numbers throughout the text. For example, “Figure 3a” in line 268 should be “Figure 5a”?

Figures 2 and 3: I’m a bit puzzled by “tropospheric SO2” mentioned in figure captions – I assume those should be total column amounts?

Figure 8: The Y-axis for the inserts needs to be marked – since different areas have different trends (as shown in Figure 5), I assume the range (in DU) for each insert is also different?

Also some further polishing would be helpful – for example in line 229, change “taken up by winter” to “from winter”.

For the reply to my second point in the specific comment, although you elaborate that “the low level SO2 columns are subject to large uncertainties and the background correction is an important source of error”, you do not make any changes in Line 151-155 of the previous manuscript. One clarification needs to be added there.