The authors should address the following comments:

Line numbers are for the version with tracking.

L. 86: I suggest you provide references for these significant advances in modelling and data assimilation, and for the additional datasets available for constraining the DAS.

L. 110: I think this statement could be ambiguous. If I understand correctly, you are discussing the coverage from NDACC data, rather than the spatial resolution – ground-based measurements can have very high spatial resolution. Is this correct?

L. 132: Where is the top level? Same for L. 138, L. 149

L. 216: What is MPVG? Acronym not introduced before (you introduce it in L. 381).

L. 237: Do you need to mention that the region is cold?

L. 262: Perhaps a bit pedantic, but poleward of 40S could also be toward the North Pole (I understand you mean in this case toward the South Pole). Could you remove this ambiguity by changing the text? You could argue this also applies to, e.g., L. 335.

L. 534: Is this improved agreement for both hemispheres?

L. 561: And for after 2002?

L. 565: Indicate that this shift is at 2002 (unless I am mistaken).

L. 575: I suggest you quantify these “small” differences.

L. 582: Identify the first 3 periods.

L. 602: Polar processing studies for both Arctic and Antarctic?

Table 1: Perhaps indicate how the acronym is built by capitalizing all relevant letters, e.g., for CHAMP.

Fig. 1: I suggest you indicate in the caption the colour scheme used. Same for other figures, e.g., Fig. 6, 10, 14, 15, 17.

Fig. 2: Are these example cases? If so, indicate.

Fig. 3: The legend above the figure is confusing, as it suggests the plot concerns the period 1979/80 – 2013/14. Perhaps remove the legend and provide this information in the caption.

Fig. 4: I suggest you remind the reader what are the coloured regions of Fig. 1. Same for other figures (e.g., Fig. 6, 8, 11, 13, 14, 15).

Fig. 5: Indicate in the caption what the colours red/blue indicate, e.g., positive/negative differences. Same for other figures, e.g., Fig. 9.

Fig. 7: Indicate that the Arctic/Antarctic correspond to the top/bottom plot. Same for other figures, e.g., Fig. 10, 12.

Fig. 16: I suggest you indicate the reanalysis (by colour) and isentropic level used in the caption.