I believe that this manuscript represents a valuable contribution to the field and will eventually be publishable. However, I agree with Anonymous Referee #1 in that a full discussion, in the main manuscript, of other possible sources and sinks of nitrate which are not accounted for in the models, and how they compare to the sources and sinks currently represented in the models (i.e., why you believe they are insignificant for this system), is warranted. I believe that by "deposition" the referee is referring to aerosol deposition, since you of course are considering different mechanisms of gas deposition here. The discussion of nitrate photolysis should be expanded upon and placed in the context of much more sophisticated treatments of nitrate photolysis in Antarctic snow in the literature (e.g. Boxe and Saiz-Lopez, ACP 2008 and Shi et al. Atmos. Chem. Phys., 15, 9435–9453, 2015 www.atmos-chem-phys.net/15/9435/2015/). And this discussion belongs in the main manuscript, not the supplement.