Dear authors,
Based on the second report by the Anonymous referee #1, I see that the manuscript is nearly ready for publications. Before acceptance, you should answer to the (mainly) technical comments provided in the Anonymous referee #1 report. Mainly, you should make sure all the figures are correctly referred within the manuscript and the spelling mistakes have been taken care of. What comes to CDO, you currently refer this using a webpage which is not good as URL's generally can change. If you wish to have the CDO sentence, you should refer to this either with DOI or with published paper etc.

Kind regards,
Leena Järvi

Dear Author,
There are a few small issues that still need to correct before the paper can be accepted. What comes to Code and data availability, following the editorial guidelines (https://www.geosci-model-dev.net/12/2215/2019/gmd-12-2215-2019.pdf) you should make the used data available also either in supplementary material, separate doi or added to zenodo where the plot code is published. So simply having text that data available upon request is not applicable.

Other minor technical comments:
P4, L20: Comma missing from the reference before et al
P5, L5: Extra parenthesis around reference year
P6, L29: Remove "from their Web site at https://www.esrl.noaa.gov/psd/"
P9, L17, L25 L27: space between Fig. 4 and Fig. 5 (and on next pages also)
P9, L29-20: extra spaces in the beginning and end of brackets.
Figure 1: Font quality not the best. Source for the figure not specified.
Figure 2, 4, 5: Quality not good particularly what comes to fonts.
Table 3: No lines in the table.

Dear Authors,
The last link to Zenodo did not work. Can you please update still this one after which I can accept the paper.

Cheers,
Leena