|This paper evaluates the simulation results on the liquid-vapor-air flow mechanisms between snowpack and soil by coupling a snow module and a soil module. The authors made great efforts to couple the models and made a detail analysis of their results. However, three major concerns are rising from the unclear purpose of this article, the weakness of the coupling method, and the unconfident results due to missing snow observation.|
1. What do the authors want to find by considering various complexities of mass and energy transfer physics? Isn't a more comprehensive parameterization scheme, without any simplification, is better for a snow-soil model? Are there any physically-based conflicts between different sub-models? Or are any sub-models a fault, so the authors had to find it out by this coupling?
2. The key of this paper is the heat-water interaction between UEB and STEMMUS-FT. However, the UEB model may not be a good choice since it considers the snowpack as a 1-layers object, ignoring the significant temperature change on different snow profiles. The authors need to clarify: 1) whether the UEB model gives the temperature of snowpack bottom since it is the most critical boundary condition for solving soil heat transfer. 2) whether the water flows from snow would bring heat to soil. If YES, how did you considered the water flow temperature? 3)whether the solar radiation penetration was considered in your method since the snowpack would be very shallow in the Tibetan Plateau.
3. The topic is the coupling between parameterizations of snow and soil. However, there is no direct snow observation such as snow depth. The ALBEDO or other variables could only provide indirect evidence. So, it is not confident for me to agree with the authors on the benefits of STEMMUS-UEB. I suggest the authors using a more comprehensive dataset to evaluate your model. Some supersites for the cold region, even in Tibetan Plateau, such as the super snow and frozen-ground observations network in Qilian mountain (Che et al.,2019), could provide enough dataset for your evaluation and similar job (Li et al., 2019).
Che, T., Li, X., Liu, S., Li, H., Xu, Z., Tan, J., Zhang, Y., Ren, Z., Xiao, L., Deng, J., Jin, R., Ma, M., Wang, J., and Yang, X.: Integrated hydrometeorological, snow and frozen-ground observations in the alpine region of the Heihe River Basin, China, Earth Syst. Sci. Data, 11, 1483–1499, https://doi.org/10.5194/essd-11-1483-2019, 2019.
Li, H., Li, X., Yang, D., Wang, J.,Gao, B., Pan, X., et al. (2019).Tracing snowmelt paths in an integrated hydrological model for understanding seasonal snowmelt contribution at basin scale. Journal of Geophysical Research: Atmospheres,124.
Line 21-22. It may not be suitable to use "the effect of snowpack on soil moisture and heat transfer" since there is the only comparison among different parametrization schemes, but not a reliable analysis of this effect based on the examined model and its proven results.
Line 69-70. Many models such as SHAW, CLM, and CROCUS all consider the underlying soil physical processes. In addition, what is the meaning of air balance in Table 1? If the air balance has notable influences on the modeling, please explain it with some references.
Section 2.1 is just like an introduction of the SEMMUS model, but the readers would be firstly interested in your methods in this paper. I suggest presenting the coupling method first and then detail the two models separately.
Line 94. What is the job this reference cited?
Line 100. It may not be the only linkage because the water flow would transfer heat and mass simultaneously.
Line 117. Why first order? A little weird.
Line 127. Could you please specify the means of the one-way?
Line 132. Did the UEB model simulates the meltwater temperature and includes it in the heat flux output? I am also interested in the temperature of the snowpack bottom that the UEB model could give or not. As the authors suggest, the UEB model assumed the snowpack as a single layer, so the snowpack temperature is very different from the underlying boundary temperature of the snowpack, which is the most crucial heat boundary for solving the heat transfer in the soil matrix. Also, solar radiation should be considered since it could penetrate about ~10 cm into the snow if there are shallow snowpacks.
Line 148-153. I am confused with the reason to set these three cases. Would you please specify the purpose, which is to find a simple but effective enough coupling method? Is it not the most reliable method to include all physical processes?
Section 2.5. Please give some information about the snow distribution and observation in this site since the soil-snow interaction is the topic of this paper. Only soil information was given here.
Line 158. The station in TP, with shallow snowpack, I strongly suggest considering the solar radiation penetration.
RESULTS part. Where are the results on snow? Would you please give a quantitative evaluation of these results?
Line 319-321. It would be true in this region, but it would be evidently given here by using data, observation, references, and so on.
Figure 1. Please clearly present the coupling variables between UEB and STEMMUS-FT.
Figure 2. It is better to present the precipitation with columns but not lines. The color between precipitation and snow should be different. In addition, the improvement with the coupling snow module is not so noticeable.
Figures 3 and 4. The difference is tiny between two cases with and without snow modules.
Figure 5. The improvement is not apparent from these results.