Review provided in the attached pdf.

Glatthor et al. is a nice manuscript introducing a new version of the 2002-2012 MIPAS ClO measurements.  It is a very welcome contribution to the available data on stratospheric ClO, both in the upper stratosphere and in the lower stratosphere during the polar winter.

Pg. 1, L. 28 - “These days, monitoring of stratospheric ClO from the ground is a routine activity”.  Yes, NDACC microwave measurements of ClO are “routine” in the sense that they are available on most days, but this sentence seems to imply that they are generally available at NDACC stations.  There are only 2 instruments measuring ClO from the ground, one at Mauna Kea and one at Scott Base.  

Pg 3. L.  8 – “For data users who prefer not to work with averaging kernels, we also provide the data on a coarse grid, where averaging kernels do not need to be applied”.  Does this mean that there are two different retrievals being performed, or just that a smoothed version of the retrieval is supplied?  

Pg 6., L. 13  - “The O3 results from the combined ClO-O3 retrieval are discarded because they are deemed inferior to the standard V8 O3 results.”  This should obviously never be the case for optimally chosen parameters for a combined ClO-O3 retrieval, but perhaps a clarification of what is meant by “inferior” would help here.  Is it just the case that occasionally the inclusion of noisy channels needed for the ClO retrieval (and not the standard O3 retrieval) cause a bad O3 retrieval?  Or does the inclusion of ClO adversely affect almost all O3 retrievals? 

Figure 3 – What does the ClO profile used here look like besides being “strongly enhanced”?  Also, it would be very helpful here if the ClO spectrum from Figure 1b  could be plotted as a third panel with the same horizontal axis as Figures 3a and 3b.  Doesn’t the fact that, wherever there is a clear red/blue difference the residual is still very negative imply that there is still not enough ClO in the model?

Pg. 14, L. 17 – “where the related averaging kernels are unity; i.e. the profiles are free of formal a priori information”.  This can never be the case.  “Near unity” and “contain minimal a priori information” would be okay.  It would be good to see these kernels as a fourth panel on Figure 4, which would also show the altitude range where these coarse resolution kernels are near unity.  

Pg. 31, L. 13 – The chemistry of the lower stratospheric peak and the upper stratospheric peak is completely different, so it’s not clear from the data here whether the differences are larger because of a larger local time difference or to differences in the sensitivity to local time.  

More generally, it would be very helpful somewhere earlier in the manuscript (perhaps on Pg. 26, if not earlier) to discuss the local times of both the MLS and MIPAS measurements, rather than to have the reader wondering about the cause of the bias between MLS and MIPAS shown in Figure 14.  Currently it is not until the final figure (Figure 18) of the paper that the sensitivity of daytime measurements to local time is discussed. 

Pg. 33, last line – “the MIPAS and MLS data observed during Antarctic winter perfectly fit to the EMAC curve”.  Since ClO in this region is dependent on the details of the presence of PSC’s and therefore, when averaged over a large latitude band, on the precise variations in local temperature, the “perfect fit” in Figure 18a for this particular date seems serendipitous.  Are the fits on other days during this period similarly good?