Dear authors,
thank you for the revisions of your manuscript. I have sent this out for review again because one of the previous reviewers suggested major revisions and demanded to see the manuscript again. Unfortunately we haven’t received a report. Therefore I am sending you a few own comments which I ask you to consider in your final revision. They mostly concern a more balanced discussion of the usefulness of the specific CryoSat NRT product for the various applications.
In most cases it is hard to see what the scientific benefits of NRT data really are. I think here is your chance to give that product and yourself a little more scientific credibility by providing a more critical view. It clearly is a remarkable achievement on ESA’s and your side to be able to provide aux data in NRT, and to carry out the processing in due time. However, these are more technical issues and do not help the science. Accordingly, your manuscript now also includes a thorough review of freeboard and thickness uncertainties, but I would argue that it is not particularly tied to the NRT data, but of more general interest. It is reassuring that the NRT data are of comparable quality as the conventional data products.
So what are NRT CryoSat data good for? And what do you mean by operational users? An evaluation needs to consider the accuracy and spatial and time resolution of the product. I would argue that one thickness retrieval every 14 or 6 km isn’t at all enough to help tactical (short-term) marine operations, and thus the product will not be useful for planning ship routes or drilling operations. In addition, you should specify what the CryoSat retrievals actually represent. Is it mean thickness, modal thickness, or maximum thickness? There seems to be some consent that it is modal thickness. However, for shipping and ice management it is the tail of the thickness distribution and the amount and thickness of the thickest ice that are of most concern.
Marine operations are mostly carried out in the summer. That is the time when your product is not available. Also you talk about the Northwest Passage a lot, but only mention briefly that the data are of lesser quality there. A more critical discussion would be desirable.
On the other end of the scale, you argue that the NRT data will improve climate models etc. I cannot see why such long-term activities and developments, and the observation of climate related changes would benefit from NRT data and couldn’t simply use the traditional products? Also what is the advantage of NRT ice volume estimates (Arctic wide?) over more regional ice thickness information?
Finally, I do think that the one and only aspect where NRT data even with monthly resolution could be useful is seasonal ice forecasting, where observed growth during the winter and ice thickness in the end of the winter could be used to evaluate the state and pre-conditioning of the ice cover in a certain year, and where late spring ice thickness data can be used to initialize forecast models to inform outlooks of general summer ice conditions. This could be helpful for e.g. strategic (long-term) navigation planning (go or not go...). This is also one of the objectives of OIB, but the CryoSat product may be more useful than the OIB data due to their larger regional coverage, at the cost of much smaller spatial resolution. Lindsay et al. (2012), for example, have shown how such data can be used for ice forecasting, and it would only be natural to suggest to do the same with CryoSat data.
I think it would be good if you could end your paper on such a note, and provide a more critical view throughout.
Thanks and best regards
Christian

Lindsay, R., Haas, C., Hendricks, S., Hunkeler, P., Kurtz, N., Paden, J., Panzer, B., Sonntag, J., Yungel, J., and Zhang J. (2012), Seasonal forecasts of Arctic sea ice initialized with observations of ice thickness, Geophys. Res. Lett., 39, L21502, doi:10.1029/2012GL053576.

Thank you for your careful replies and their implementation Rachel!
Regards
Christian