I really enjoyed reviewing this paper. It is well written and presents some very interesting and significant results regarding frazil ice generation. It includes an excellent review of previous models and related papers that was well organized and easy to follow. The paper requires only some minor revisions before it is acceptable for publication. I have provide minor comments in the attached PDF file.

The manuscript analyses sources of uncertainty in modelling frazil ice. Frazil-ice processes are complex but are geophysically significant in a range of cryospheric settings. The manuscript falls within the scope of The Cryosphere. The manuscript analyses a wide body of literature in a thorough and careful fashion and includes lots of helpful review/analysis. It then undertakes a systematic formal uncertainty analysis which is a worthwhile novel advance in the field; in contrast previous analysis was more ad hoc and based on a limited exploration of parameter space. The manuscript compares single and multiple-size-class models and finds that (within the types of experiments considered), single-class models can be tuned to match the results of multiple-size-class models. Different sources of uncertainty in different types of models are systematically quantified and discussed. While the type of calculations are limited to examples motivated by simple laboratory experiments (and the picture may be more complex in the field), this study achieves significant and worthwhile results within its context. The paper is well written, thorough and insightful and should be published subject to the minor comments attached.