Dear Authors:

I now have the two reviewer reports of your revised m/s (included below along with my comments) and some minor revisions are required before accepting your paper. Most of these comments are easily dealt with but Figure 8 and the associated analysis will need to be revised or removed as the current data do not support your conclusions. Corrections are also needed to the referencing of ERA-Interim.

I look forward to your response.

Best regards, Ross Brown

Review comments on revised m/s:

Reviewer 1
- line 120: There are two dots (..).
- p. 23, About channel morphology control on ice break-up, I suggest to read and to add this reference in the discussion. DE MUNCK*, S, GAUTHIER*, Y. BERNIER, M., POULIN*,J. CHOKMANI, K. (2011) Preliminary development of a geospatial model to estimate a river channel’s predisposition to ice jams. CGU HS Committee on River Ice Processes and the Environment (CRIPE), 16th Workshop on the Hydraulics of Ice Covered Rivers, September 18 – 22, Winnipeg, Manitoba, 11 pages.
- The authors could be interested to read some papers about River Ice Monitoring in the Proceedings of the 18th Workshop on the Hydraulics of Ice Covered Rivers, Quebec City, QC, Canada, August 18-20, 2015. http://www.cripe.ca/

Reviewer 2:
- The interpretation of Fig 8 around lines 85-95 needs to be significantly improved (as I noted already in my first review, but wrongly referring to albedo, instead of Precip and Air Temp). The authors' interpretation about correlation between precip and temp, and break-up anomaly, seems rather random to me. I find for instance years with similar break-up anomalies, but different ones for precip and temp. (e.g. 2005, 2007 and 2010). Also else I cannot really follow the authors discovering a clear correlation. To make this 'visual' statistics acceptable for publication, the authors need to provide quantitative standard statistical measures, in that case multvariate ones, that show that the correlation claimed is not a just a random product, but statistically significant.

Editor comments:
- Given your short period of data, I suggest you revise your abstract to focus more on the novel aspects of your methodology.
- Lines 83-84: Brown and Derksen (2013) is not an appropriate reference for ERA-interim. The recommended citation is Dee et al. (2011). Also, ERA-interim is currently available up to July 2015 so the comment “until 2011 only” is incorrect.
Dee, D. P., Uppala, S. M., Simmons, A. J., Berrisford, P., Poli, P., Kobayashi, S., ... Vitart, F. (2011). The ERA-Interim reanalysis: configuration and performance of the data assimilation system, Q. J. R. Meteorol. Soc., 137, 656, DO -10.1002/qj.828
- I agree with Reviewer 2 that your interpretation of Figure 8 is not supported by the data. From eyeballing the numbers off your figure there is only a weak correlation between air temperature and break-up (-0.4 which is not statistically significant for the sample size). The correlation between break-up and precipitation is close to zero. I tried a multiple regression of break-up on temp and precip and neither of the variables was a significant predictor. The only significant correlation I could find is between temperature and precipitation (cold winters have higher precip and vice versa). You may get more significant results with 2012 and 2013 included but I have my doubts. You might also think about looking at other climate indices more closely related to ice growth and/or ice break-up processes e.g. some of the empirical expressions presented in Bilello (1961) based on the sum of freezing degree-days http://pubs.aina.ucalgary.ca/arctic/Arctic14-1-2.pdf. Variability in the dates of the zero isotherm (following the work of Prowse et al. 2007) may also be worth investigating. This reference would be an appropriate addition to your literature review.

T.D. PROWSE, B.R. BONSAL, C.R. DUGUAY, M.P. LACROIX, 2007: River-ice break-up/freeze-up: a review of climatic drivers, historical trends and future predictions. Annals of Glaciology 46: 443-451.

I am pleased to accept your revised paper for publication. Congratulations and thank you for submitting your paper to TC.

Best regards, Ross Brown (Ed.)