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The paper by Malina et al. presents an ozone profile retrieval approach using CrIS thermal infrared measurements which is slightly improved by a sequential combination with TROPOMI/Sentinel 5P ultraviolet measurements. The method used in the approach and the results are sound. This is well in the scope of AMT. However, the ozone retrievals of the combined CrIS/TROPOMi approach are very similar to those from the CrIS only approach, both in terms of sensitivity and the derived ozone quantities. This mean that the contribution of the combination with TROPOMI is very limited. Since this very important aspect is not very clear in the text of the manuscript, I strongly recommend major revisions of the paper before considering publication. Moreover, the presentation of the method is not very clear and needs thorough revision.

The principal major revisions I strongly recommend are the following:

• Title: I recommend indicating explicitely that it is a sequential approach from CrIS only to CrIS/TROPOMI and replacing “augmented by” by “and”. The augmentation from TROPOMI is very limited in order to point it out so clearly in the title.
• Abstract (major remark 1): the enhancement of CrIS-TROPOMI with respect to CrIS only approach should be clearly quantified with precise numbers. The values of degrees of freedom and precision (bias, correlation, rmse) with respect to reference measurements (ozonesondes) for both the stratosphere and troposphere should be clearly provided in the abstract for both CrIS-TROPOMI and CrIS only methods.
• Abstract (major remark 2): it should be clearly stated that the approach is a sequential method first using CrIS only measurements, then TROPOMI data and finally CrIS and TROPOMI jointly. This information is very hard to find in the paper (it only appears in page 15) and it is essential to understand the clear similarity between CrIS only and CrIS-TROPOMI approaches. It should clearly state in the abstract and at the beginning of the presentation of the approach (current section 3).
• Abstract (major remark 3): The sentence “The results demonstrate that CrIS/TROPOMI retrieval have the potential to substantially improve our understanding of ozone” is too vague and unclear. The paper mainly focuses on the observation of ozone and its precision, and not on the geophysical understanding of ozone-related processes and its evolution. I recommend removing such statement and focus on the metrology aspect of the new approach.
• Section 3: A change in the order and explanations in this section is clearly needed to understand the new aspects of the CrIS/TROPOMI approach. I strongly recommend providing at the beginning a clear description of the main flow of information about the ozone profile, clearly stating which is the first approach applied (CrIS only), whose results are then used as a priori of subsequent approaches, etc. This is provided in page 15 (section 3.4) and therefore it is difficult to follow. After this overall explanation, I recommend explaining the details of each box in Figure 1 (current section 3.2, then 3.3 and finally current explanations of section 3.1).  
• The differences between CrIS/TROPOMI and CrIS only should be clearly pointed out. Currently this is very difficult to find. For example, no statements of such kind are given for Fig. 7, although it is the global comparison of ozone retrievals.
• The comparison with ozonesondes is expected to be presented before that with respect to other datasets (models, other retrievals) as they are reference measurements.
• It is very important to show correlation coefficients and global scores of the comparison between CrIS/TROPOMI and single band retrievals with respect ozonesondes (Tables 8 and 9)

Other important remarks:

• Panels in Figures: I recommend assigning different letters for each panel of the figures. Currently many panels are indicated by the same letter, which is then difficult to point out without ambiguity
• Figures 4, 5 and 6: differences between CrIS only and CrIS/TROPOMI are very tiny. I recommend providing clear statements with quantified differences.
• Quality assessment: Lines 397-400: what about convergence to small spectral residuals of the CrIS/TROPOMI retrieval as compared to CrIS only? How it is possible to have a pass rate of 39% for TROPOMI only and (slightly) larger (40%) for CrIS/TROPOMI which is subsequential step?
• Figure 7: too many tiny panels. I recommend using 2 pressure levels and much bigger panels, as well as indicating in the text the clear similarity between CrIS only and CrIS/TROPOMI retrieved ozone amounts.

Minor revisions:

• Line 273: panel c) of Fig. 1?
• 5 b) TROPOMI: color scale is saturated. It should be changed.
• Figure 15: problem with panel indicators