Simulating black carbon and dust and their radiative forcing in seasonal snow: a case study over North China with  field campaign measurements

Zhao, C.; Hu, Z.; Qian, Y.; Ruby Leung, L.; Huang, J.; Huang, M.; Jin, J.; Flanner, M. G.; Zhang, R.; Wang, H.; Yan, H.; Lu, Z.; Streets, D. G.

doi:https://doi.org/10.5194/acp-14-11475-2014

Articles | Volume 14, issue 20

Atmos. Chem. Phys., 14, 11475–11491, 2014

https://doi.org/10.5194/acp-14-11475-2014

© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.

Special issue: The community version of the Weather Research and Forecasting...

Special issue: Coupled chemistry–meteorology modelling: status and...

Atmos. Chem. Phys., 14, 11475–11491, 2014

https://doi.org/10.5194/acp-14-11475-2014

© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 14, issue 20

Research article 30 Oct 2014

Research article | 30 Oct 2014

Simulating black carbon and dust and their radiative forcing in seasonal snow: a case study over North China with field campaign measurements

C. Zhao et al.

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Final revised paper (published on 30 Oct 2014)
Preprint (discussion started on 23 May 2014)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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RC C3702: 'Review of Zhao et al., ACPD, 14, 13331-13379', Anonymous Referee #1, 17 Jun 2014
RC C3800: 'Interactiv e comment on “Simulating black carbon and dust and their radiative forcing in seasonal snow: a case study over North China with field campaign measurements” by C. Zhao et al.', Anonymous Referee #2, 18 Jun 2014
AC C6157: 'Response to the comments from the two referees', Chun Zhao, 23 Aug 2014

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Chun Zhao on behalf of the Authors (25 Aug 2014) Author's response Manuscript

ED: Referee Nomination & Report Request started (27 Aug 2014) by Ari Laaksonen

RR by Anonymous Referee #1 (29 Aug 2014)

Suggestions for revision or reasons for rejection

The paper has been sufficiently revised that it is very nearly suitable for publication. Overall the paper could use some editing for English/clarity/flow by ACP, as well as a few other very small changes. I note some examples of corrections to English below, but a more careful job by an editor would be very beneficial.

There is one thing I would like to see added, and I leave it to the editor to decide whether this is necessary for publication:
Both reviewers found the very large range in simulated BCS (Fig 7) surprising. In the replies to reviews, the authors explain why these values exist in the simulated BCS values but no such explanation has been added to the paper itself. I think the fact that both reviewers found this surprising means other will too, and therefore it merits some explanation in the paper itself. In the explanatory example shown in the reply (Figure r3), the large range in BCS is a result of there being effectively no new snow added to the snowpack after an initial snowfall (days 1-2 of the simulation). During the approx. 4 days following a snowfall event, there is a step-wise loss of snow water (presumably to a combination of sublimation and melt) and the addition of BC (presumably through dry deposition). In the model, I understand that when the top layer thickness decreases sufficiently, snow and the BC mixed with that snow from the layer below the surface are re-combined into the model top snow layer. However, before reaching this threshold that triggers layer “recombination”, snow water is lost as an increasingly thin layer of the snowpack is being included in the “top layer”. Thus, this thin layer will preferentially have snow water removed and BC added. So a question is whether some of the change (here, an increase) in BCS is due to the top layer becoming thinner and thinner, with this thinning top layer retaining most of its BC but losing its snow water. In other words: Would this same range in BCS be seen if the “top snow layer” was defined over a fixed snow depth? I don’t actually expect the authors to conduct a full analysis to answer this question, but I do think they should point out what is shown in Figure r3 in terms of the mechanisms that drive the large range in BCS in a short period of time. They should also note the possible effects of having a variable depth to the “top snow layer” on “top layer BCS”.

Following are the minor revisions needed to make the paper acceptable for publication (along with some editing for English):

Section 2.1.1 and 2.1.2 titles need to be capitalized

line 365: As noted in my original review, it should be made very clear up front that this data set is someone else’s work. One still gets the initial impression the field measurements are part of the work being reported. e.g., the first sentence could be revised as follows: “The primary observational dataset used in this study to evaluate the model simulations of snow and BC content in snow is from a field campaign described by Huang et al. (2011), where they collected seasonal snow in January/February 2010 on a road trip at 46 sites in North China.”

line 387: “NCC” needs to be defined or (better), get rid of this acronym. It is only used 6 times and readability would be improved by instead just spelling out “the North China campaign”.

line 470: “There was no BCS data available for sites 41-46”. I believe you mean “Estimates of BC in snow were not available for sites 41-46”. (Other data/parameters are available for these sites).

line 475: A period is missing at the end of this sentence.

line 586: please replace “SSA complements” with “co-albedo”

line 588: “… unlike BC that always reduces snow albedo” --> “…unlike BC, which always reduces snow albedo”

line 606: “Although, dust is much less…” --> remove the comma after “Although”

line 611->612: “reduce radiation reaching surface” --> “reduce radiation reaching the surface”

line 613: “warming in snow shows higher magnitude in south than in north” --> “warming in snow shows higher magnitude in the south than in the north

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ED: Reconsider after minor revisions (Editor review) (04 Sep 2014) by Ari Laaksonen

AR by Chun Zhao on behalf of the Authors (05 Sep 2014) Author's response Manuscript

ED: Publish as is (13 Sep 2014) by Ari Laaksonen