Aerosol optical properties and direct radiative forcing based on measurements from the China Aerosol Remote Sensing Network (CARSNET) in eastern China

Che, Huizheng; Qi, Bing; Zhao, Hujia; Xia, Xiangao; Eck, Thomas F.; Goloub, Philippe; Dubovik, Oleg; Estelles, Victor; Cuevas-Agulló, Emilio; Blarel, Luc; Wu, Yunfei; Zhu, Jun; Du, Rongguang; Wang, Yaqiang; Wang, Hong; Gui, Ke; Yu, Jie; Zheng, Yu; Sun, Tianze; Chen, Quanliang; Shi, Guangyu; Zhang, Xiaoye

doi:https://doi.org/10.5194/acp-18-405-2018

Articles | Volume 18, issue 1

https://doi.org/10.5194/acp-18-405-2018

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

Special issue:

Regional transport and transformation of air pollution in...

https://doi.org/10.5194/acp-18-405-2018

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

Articles | Volume 18, issue 1

Research article

|

15 Jan 2018

Research article |

| 15 Jan 2018

Aerosol optical properties and direct radiative forcing based on measurements from the China Aerosol Remote Sensing Network (CARSNET) in eastern China

Huizheng Che, Bing Qi, Hujia Zhao, Xiangao Xia, Thomas F. Eck, Philippe Goloub, Oleg Dubovik, Victor Estelles, Emilio Cuevas-Agulló, Luc Blarel, Yunfei Wu, Jun Zhu, Rongguang Du, Yaqiang Wang, Hong Wang, Ke Gui, Jie Yu, Yu Zheng, Tianze Sun, Quanliang Chen, Guangyu Shi, and Xiaoye Zhang

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Final revised paper (published on 15 Jan 2018)
Supplement to the final revised paper
Preprint (discussion started on 26 Jun 2017)

Interactive discussion

Status: closed

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

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RC1: 'Review of Che et al. “Aerosol optical properties and instantaneous radiative forcing based on high temporospatial resolution CARSNET ground-based measurements over eastern China”.', Anonymous Referee #1, 28 Jul 2017
- AC4: 'responese to reviewer 1', Huizheng Che, 30 Aug 2017
RC2: 'RC2', Anonymous Referee #2, 31 Jul 2017
- AC2: 'response to reviewer2', Huizheng Che, 30 Aug 2017
RC3: 'Comments to "Aerosol optical properties and instantaneous radiative forcing based on high temporospatial resolution CARSNET ground-based measurements over Eastern China" by Chen et al. (acp-2017-530)', Anonymous Referee #3, 06 Aug 2017
- AC3: 'response to reviewer3', Huizheng Che, 30 Aug 2017
AC1: 'resonse to reviewer1', Huizheng Che, 30 Aug 2017

Peer-review completion

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

AR by Huizheng Che on behalf of the Authors (30 Aug 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (31 Aug 2017) by Zhanqing Li

RR by Anonymous Referee #1 (06 Sep 2017)

RR by Anonymous Referee #3 (18 Sep 2017)

Suggestions for revision or reasons for rejection

I found authors have addressed most of the reviewers’s comments to improve the quality of the article. I only have a few minor and technical comments for the authors to consider.

1. In terms of the paper structure, I still think it is not appropriate to present the validation of MODIS AOD in section 3.2. This section presents the aerosol optical properties from Sun Photometers, and satellite of validation belongs to one of the applications of the CARSNET products. So, please consider to use a standalone section for MODIS validation.

2. Line 39-40: “volume fraction” means the fraction of volume, which is not appropriate to be used as volume. I recommend to replace it with “modal volume” or “fractional volume". And the units of volume here should um^3/um^2, volume of aerosol particle per um^2 area. This correction should be applied across the entire article.

3. Line 42: 440nm -> 440 nm. This also applies elsewhere in the article.

4. Line 48: 10km -> 10 km; 3km -> 3 km. Again, elsewhere in the article.

5. Line 54-57: First, change "radiative forcing” into “direct radiative forcing”, because indirect radiative forcing was not considered. Second, it lacks innovation to simply say “aerosols causes negative forcing ...”, because negative radiative effect of aerosol over low-reflectivity surface has been well known. So, present the numbers. Third, it reads “… the lower surface albedo in a unique geographical climate condition of better vegetation in the YRD region than in north/northeast China.” So, does it means that aerosols in north/northeast China exert a positive radiative effects? Please make it clear.

6. Figure 1: I don’t see any description of the two red river lines on the map. Description maybe needed in the figure caption, otherwise, consider to remove them.

7. Lines 222, 406, 464, and 557: Redundant section titles. Consider to remove “Aerosol optical properties of"

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ED: Reconsider after major revisions (21 Sep 2017) by Zhanqing Li

AR by Huizheng Che on behalf of the Authors (15 Nov 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (16 Nov 2017) by Zhanqing Li

RR by Anonymous Referee #1 (26 Nov 2017)

RR by Anonymous Referee #3 (29 Nov 2017)

Suggestions for revision or reasons for rejection

I found the revised manuscript is significantly improved. I have a few minor comments in below that author should consider to address.

Specific comments:

1. It maybe necessary to include one additional important assumption in AERONET inversion products. That is, the complex refractive index is assumed independent of particle size. In other words, the inversion algorithm [Dubovik et al., 2000, 2006] gives the same refractive for both fine and coarse modes. This assumption valid for fine or coarse-dominated cases, however, could cause error in SSA and even particle size for mixed aerosol scenarios. This issue has been discussed by Xu and Wang [2015] and Xu et al [2015]. The same studies also made efforts to retrieve mode-dependent aerosol complex refractive indices and SSA.

2. The quality of most figures needs improvements. In particular, the font size of plots and legends should be enlarged.

3. Line 161-162: The description of fine and coarse mode separation may be incorrect here. Please verify. According to the official description of AERONET inversion Products, "the inversion code finds the minimum withinthe size interval from 0.439 to 0.992 μm. This minimum is used as a separation point between fine and coarse mode particles. Using that separation, the code simulates optical thickness, phase function and single scattering albedo of fine and coarse mode separately. Furthermore, the retrieval provides estimates of Effective Radius reff, Volume Median Radius reff, Standard Deviation σ and Volume concentrationsCv (μm3/μm2) for both fine and coarse modes of the retrieved size distribution.” Source: https://aeronet.gsfc.nasa.gov/new_web/Documents/Inversion_products_V2.pdf

4. Line 242-244: “.., but the range of effective radii was greater, possibly due in part to the lower retrieval accuracy for coarse particles compared with the fine-mode.” This confuses me, as coarse-mode effective radius seems not quite dispersed among different sites (according to Table 1). Please double check.

5. Line 322: The abbreviation “FMF” needs to be defined. And, is the FMF in terms of particle volume?

References:
Xu, X., and J. Wang (2015), Retrieval of aerosol microphysical properties from AERONET photopolarimetric measurements: 1. Information content analysis, Journal of Geophysical Research: Atmospheres, 120, 7059–7078, doi:10.1002/2015JD023108.
Xu, X., et al. (2015), Retrieval of aerosol microphysical properties from AERONET photopolarimetric measurements: 2. A new research algorithm and case demonstration, Journal of Geophysical Research: Atmospheres, 120, 7079–7098, doi:10.1002/2015JD023113.

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ED: Publish subject to minor revisions (review by editor) (29 Nov 2017) by Zhanqing Li

AR by Huizheng Che on behalf of the Authors (29 Nov 2017) Author's response Manuscript

ED: Publish as is (04 Dec 2017) by Zhanqing Li

AR by Huizheng Che on behalf of the Authors (05 Dec 2017) Manuscript

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Short summary

Sun photometer measurements from seven sites in the Yangtze River Delta (YRD) from 2011 to 2015 were used to characterize the climatology of aerosol microphysical and optical properties, calculate direct aerosol radiative forcing (DARF) and classify aerosols based on size and absorption. This study contributes to our understanding of aerosols and regional climate/air quality, and the results will be useful for validating satellite retrievals and for improving climate models and remote sensing.