|Review to Fugger et al. (2021): "Understanding monsoon controls on the energy and mass balance of glaciers in the Central and Eastern Himalaya" submitted to The Cryosphere.|
The authors present a study of surface energy and mass balances during different climatic regimes, the pre-monsoon and the core monsoon season, at different glaciers in the Himalaya. Interestingly, the glaciers represent sites with thick, thin or without debris cover. From observations and modelling at the point scale the authors derive the energy and associated mass fluxes and show, that depending on the surface type, the monsoon influence is either minimal or enhancing melt compared to the pre-monsoon season.
The manuscript is long and dense but the structure is well built and makes it easy to read. The hypotheses are clearly laid out and the methods are well explained. The discussion section brings up the questions asked in the hypotheses and gives concrete answers with a generalized figure (Fig 8) as overview of the regime changes and impacts on different glacier sites. Figures are coherent and help the reader understanding the key points. The substantial supplementary material supports data and results.
Overall, I rate the manuscript ready for publication after clarifying some minor comments.
Specific comments referring to manuscript version 3:
L 131, Equations 1-3: I'd suggest to generally write the energy balances as addition, i.e. without any minus symbol. All fluxes (except SWnet) can switch sign and the sign they receive in the equation depends on the sign convention used (and explained in L 142). According to this, M must receive a negative sign as it denotes the available energy flux for melt, which removes energy from the surface by phase change. This has implications on the sign of M in several figures and tables.
L 140: I suggest a rephrasing. In the given form of Eq 1, M is the available energy for melt, not the net energy input into the snow or ice. We just make it the net "input" by solving the equation for M, but note, the sign must be negative according to convention in L 142.
L 177, section 3.1.4: All equations and parameters are well defined. I just miss an explicit explanation of the aerodynamic resistances (rah and raw) and their control of atmospheric stability. This could go into the supplementary material.
L 198: Controls on turbulent fluxes. I'd remove this paragraph here and put it into the supplementary material as well with a bit more information on the regression. For now, this information is a bit lost and becomes relevant in Fig 7a only, where a reference to the supplementary material could be made.
L 306, section 3.5 Model evaluation: Could you add information of evaluating against surface temperature? A table of RSME would be enough.
L 323: Please correct. In Fig 4 you say the value is 43.4 mmd-1.
L 345: Do you mean air or surface temperatures or both?
L 353: There is something missing at the end of the sentence, I think.
L 413: Is it possible to say, whether this wind is katabatic or synoptic?
L 542: Does this mean that climate change even enhances the transition from clean ice (or thin debris covered) glaciers to thick debris covered glaciers?
L 602: The definition of the monsoon onset and recession seems not easily reproducible. Could you give more information, e.g. if you have an order of the variables you look at first, or if you define thresholds, etc.
Table 1: Please, add the distance between AWS and precipitation measurement site.
Table 2: Glacier elevation: For glaciologists the median elevation would be more interesting than the mean.
Table 4: Seems like it happened accidentally to be a duplicate of Table 3.
Table 5: What is ea? This was not explained before, I think. What was the reason to choose a 3% range of the radiative fluxes? Wouldn't it make more sense to choose the range from the given sensor error, which might be a bit larger? (I see no need for a repeated analysis, I'm just curious.)
Figure 7b: Very interesting information. Thank you for showing this.
Figure 8: Good overview. I just wonder why G and M are not displayed as triangles. They are incoming and outgoing fluxes as well.