Light absorption of brown carbon in eastern China based on 3-year multi-wavelength aerosol optical property observations and an improved absorption Ångström exponent segregation method

Wang, Jiaping; Nie, Wei; Cheng, Yafang; Shen, Yicheng; Chi, Xuguang; Wang, Jiandong; Huang, Xin; Xie, Yuning; Sun, Peng; Xu, Zheng; Qi, Ximeng; Su, Hang; Ding, Aijun

doi:https://doi.org/10.5194/acp-18-9061-2018

Articles | Volume 18, issue 12

https://doi.org/10.5194/acp-18-9061-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

Pan-Eurasian Experiment (PEEX)

https://doi.org/10.5194/acp-18-9061-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 18, issue 12

Research article

|

28 Jun 2018

Research article |

| 28 Jun 2018

Light absorption of brown carbon in eastern China based on 3-year multi-wavelength aerosol optical property observations and an improved absorption Ångström exponent segregation method

Jiaping Wang, Wei Nie, Yafang Cheng, Yicheng Shen, Xuguang Chi, Jiandong Wang, Xin Huang, Yuning Xie, Peng Sun, Zheng Xu, Ximeng Qi, Hang Su, and Aijun Ding

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

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RC1: 'Review of light absorption of brown carbon', Anonymous Referee #1, 02 Mar 2018
- AC1: 'Reply to Referee #1', Aijun Ding, 06 May 2018
RC2: 'Interactive comment on “Light absorption of brown carbon in eastern China based on 3-year multi-wavelength aerosol optical property observations at the SORPES station and an improved Absorption Ångstrom exponent segregation method” by Jiaping Wang et', Anonymous Referee #2, 02 Mar 2018
- AC2: 'Reply to Referee #2', Aijun Ding, 06 May 2018
RC3: 'Comments for Light absorption of brown carbon in eastern China based on 3-year multi-wavelength aerosol optical property observations at the SORPES station and an improved Absorption Ångstrom exponent segregation method', Dantong Liu, 05 Mar 2018
- AC3: 'Reply to Referee #3', Aijun Ding, 06 May 2018

Peer-review completion

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

AR by Lorena Grabowski on behalf of the Authors (29 May 2018) Author's response

ED: Referee Nomination & Report Request started (29 May 2018) by Veli-Matti Kerminen

RR by Anonymous Referee #2 (08 Jun 2018)

RR by Dantong Liu (10 Jun 2018)

Suggestions for revision or reasons for rejection

Thanks for the careful revision of the article, the addition of SP2 data help with the final products presented. I would recommend publication after addressing a few technical issues:

-Would you need to assume the BC refractive index of (2.26,2,16) (Moteki et al., 2010) to calculate the Dp/Dc at SP2 wavelength 1064nm?

-why not set BC refractive index according to (Bond and Bergstrom, 2006).

-Fig. 2a should be improved for clarification, such as using lines and markers, there seems to be a step change at 110nm? Is it dN/dlogDp? Or dM/dlogDp,I would suggest a clear unit for this.

- Fig. 2b, also related to the methodology section, is the Dp distribution for all populated BC, or for specified Dc range? Would be better to show the Dp/Dc distribution rather than Dp, as Dp/Dc is the one to reflect coating thickness (given winter Dc is larger).

-Eq 6. seems crucial, I think it needs to be clearer how you obtained the scaling factor of AAE. There are some difference between SP2 derived AAE and Aeoth measured one (would this be partly because there is still small BrC absorption at green), could you do scatter plots for all seasons and make this number more robust.

-would be helpful to give a time series of your corrected AAEBC which have been finally used.

-I still a bit struggle to understand the application of Babs/K+. Because K+ is mainly for open biomass burning, whereas levoglucosan is generally for more smouldering such as residential burning maybe. Fig. 5a clearly showed the periodic peak of K+ in May and Jun. so Fig. 8 is simply because the crop burning has more K+ emission (if emitting the same amount of OM)?

Bond, T. C., and Bergstrom, R. W.: Light absorption by carbonaceous particles: An investigative review, Aerosol Sci. Tech., 40, 27-67, 2006.
Moteki, N., Kondo, Y., and Nakamura, S.-i.: Method to measure refractive indices of small nonspherical particles: Application to black carbon particles, J. Aerosol Sci., 41, 513-521, 2010.

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ED: Publish subject to minor revisions (review by editor) (11 Jun 2018) by Veli-Matti Kerminen

AR by Aijun Ding on behalf of the Authors (17 Jun 2018) Author's response Manuscript

ED: Publish as is (18 Jun 2018) by Veli-Matti Kerminen

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Short summary

An optimized segregation method is applied to estimate light absorption of brown carbon (BrC) in Nanjing. This study highlights the considerable contribution of BrC to light absorption in the Yangtze River Delta region, China, and depicts its long-term profile in this region for the first time. Lagrangian modeling and the chemical signature observed at the site suggested that open biomass burning and residential emissions are the dominant sources influencing BrC in the two highest BrC seasons.