All four referees were positive about the paper and agreed that it should be accepted after minor revision. My impression is that you have undertaken revision thoroughly and certainly you have provided a very detailed set of responses to referees, including explanatory figures, which will of course be available to readers in the online documentation on this paper after publication in ACP.

Bearing in mind your thorough response and revision I do not see any need to consult the referees further and I am pleased to accept the paper for publication in ACP.

I have noted a small number of minor points below that I invite you to consider as possible technical corrections before publication.

p4 l25: 'Furthermore, it is not feasible to determine exactly what observational data were actually assimilated at each data assimilation analysis step (e.g., what data quality control and bias correction procedures were actually applied).' One of the referees criticised this statement -- taking the view that such information must be available somewhere. One issue is availability of information. Of course, each re-analysis was introduced by some kind of publication and you have cited those publications at the beginning of Section 2. But I guess that these publications do not contain absolutely every detail of the reanalysis. A distinct issue is any publication can only have finite scope -- not every detail can be covered. Which are you trying to emphasise? Perhaps you are trying to emphasise both? A minor change of text to something like -- 'However, we believe it is interesting to investigate representations of key phenomena in the reanalyses and we hope that such investigation ...' might give a reader a more positive impression.

p6 l19: Another topic raised by referees was re MERRA-2. You justify why you don't give MERRA-2 full consideration, but that could be a bit clearer. For example, before you say ‘For these
reasons, our study focuses mainly on the five reanalyses: ERA-40, ERA-I, JRA-25, JRA-55 and MERRA.’ — it perhaps confusing to mention immediately before that MERRA-2 has improved the QBO. I suggest that you make it clear that the reasons are provided in the previous 2 paragraphs (not just the same paragraph) and that you move sentence about improved QBO to after the statement above. -- e.g '(But note that MERRA-2 shows some improvement ....)'

p17 l25: ‘Padglajen’ > ‘Podglajen’ (as in reference list)