Dear Qi Ling and colleagues,
I am pleased to accept your manuscript for publication in ACP, subject to the technical corrections below,
Sincerely,
Rob MacKenzie
P1, line 12: should be “the western side of the extreme north of Russia”
P1, line 13: “exceedingly” should be “too”
P1, line 14: change “the dry” to “a dry”
P1, line 19: change “of BC” to “of clouds for BC”
P1, lines 28-29. Containing two contradictory ideas in a single sentence using paraetheses is an increasingly common way to save space, but is bad practice in written English. Please replace with “Doubling precipitation introduces a positive bias approximately as large as the overall effects of flaring emissions and the WBF effect; halving precipitation produces a similarly large negative bias.”
P1, line 31 aerosol, not aerosols; influences, not influence
P2, line 9: unexpectedly, not unexpected
P2, line 14. I suggest “the diagnosis and prediction of BC_snow” because your paper uses a CTM
P3, line 6: should be “in a disproportionately large”
P3, line 13: should be “scavenging efficiency in clouds”
P3, line 28: constraint, not constrain
P4, lines 6-8: are these sources of error really two-sided? The under-catch and loss to plastic flakes sound to me like they give rise to a low bias rather than a two-sided uncertainty.
P4, line 11: “0.66 km above mean sea-level (a. s. l.))”
P5, line 2. The logic here does not follow: land at any altitude has a boundary layer associated with it. I suggest you re-write the sentence to say simply: “The Summit site is at high elevation (3.2 km a. s. l.) and surrounded by flat homogeneous terrain.”
P5, line 20: the GEOS-Chem model cannot have 2 x 2.5 degree resolution near the pole. Please add a sentence explaining how the polar singularity is dealt with.
P5, line 34ff: you might like to cite the recent review by Fawole et al., particularly regarding the variability in emission factors – at your discretion, this is not a stipulation:
Fawole, O.G., Cai, X.M. and MacKenzie, A.R., 2016. Gas flaring and resultant air pollution: A review focusing on black carbon. Environmental Pollution, 216, pp.182-197.
P7, line 20: I suggest “BC-containing aerosol particles in water drops which evaporate to dryness are released…”
P8, line 11: remove repeated sentence.
P8, line 23: “snow distribution; this process is difficult to simulate in global models.”
P8, line 25: sublimation, not sublimations
P8, line 25: “we filtered out…”
P8, line 35: “(Sect. 3.3) as well as the gas-flaring emissions”
P8, line 35: “The difference … denotes”
P8, line 36: “(Sect. 3.4) as well as the gas-flaring and v_d updates.”
P9, line 2. Please add a sentence along these lines: “In our discussion of the results of the model runs, we assume that there is little or no interaction between each of the updates, i.e., that the order in which the processes have been included does not affect the overall results.”
P9, line 21: two-fold, not two-folded
P10, line 35: circumpolar transport can’t carry material to the high Arctic – I suggest you delete this sentence or at least the word ‘circumpolar’.
P11, line 2: depends, not depend; varies, not vary (or change v_d to ‘the deposition velocities’)
P12, line 14: I suggest “Inclusion of a parameterisation of the WBF process in the model suppresses the scavenging of BC in model mixed-phase clouds and consequently…”
P12, line 17: I suggest “The parameterised WBF process not only increases BC_snow in the model Arctic, but also…”. And “Our model results find…”. And “… indicating that the fraction in the Arctic is more sensitive to the WBF parameterisation in our model.”
P12, line 26: “strongly affected by the WBF parameterisation…”
P12, line 29: “in the Arctic in our model.”
P12, line 33: “This modelling result is consistent…”
P13, line 11: “Our model results show that the WBF parameterisation…”
P13, line 13: “The WBF parameterisation has the effect of suppressing…”
P13, line 18: aerosol, not aerosols
P14, line 5: delete “It is conceivable that”
P14, line 35: “in this region of the model”
P15, line 4: “…in most previous estimates.”
P15, lines 6-7: “(Sect. 4.1), including gas flaring emissions in modelling Arctic BC appears to be justified from our results.”
P15, line 11: “than to v_d and WBF”
P15, line 12: “by 19% in the model.”
P15, line 12: “In the model, doubling precipitation in the Arctic increases BC deposition by 8%; halving precipitation decreases BC deposition by 18%.”
P15, line 12: “Total modelled BC emissions in the Arctic are a factor of two to five lower than total modelled BC deposition, suggesting that a large fraction of BC deposited in the Arctic is from long-range transport.”
P15, line 17: please correct superscripting in units
P15, lines 25-27. See my previous comment on this form of words.
P15, line 29: “Modelled BC loading…”
P15, line 32: change v_d to deposition velocities; “…which are, in some cases, a factor of two to three larger than the default value of 0.03 cm s-1”
P15, lines 34-35: this seems to repeat info from the paragraph above. Please check that this section is consistent with respect to the size of the effect of halving precipitation (ie 18% or 12%). The problem here may be that I’m not sure what you mean by ‘loading’ – atmospheric concentration? Integrated emissions? Integrated deposition?
P16, line 12: please replace hyphen with colon and space. Replace than with then.
P16, line 13: ‘used the’, not ‘implied’
P16, line 17: changes, not improvements
P16, line 27: please re-write to remove contradiction in parentheses.