Aerosol optical properties in the southeastern United States in summer &ndash; Part 1: Hygroscopic growth

Brock, Charles A.; Wagner, Nicholas L.; Anderson, Bruce E.; Attwood, Alexis R.; Beyersdorf, Andreas; Campuzano-Jost, Pedro; Carlton, Annmarie G.; Day, Douglas A.; Diskin, Glenn S.; Gordon, Timothy D.; Jimenez, Jose L.; Lack, Daniel A.; Liao, Jin; Markovic, Milos Z.; Middlebrook, Ann M.; Ng, Nga L.; Perring, Anne E.; Richardson, Matthews S.; Schwarz, Joshua P.; Washenfelder, Rebecca A.; Welti, Andre; Xu, Lu; Ziemba, Luke D.; Murphy, Daniel M.

doi:https://doi.org/10.5194/acp-16-4987-2016

Articles | Volume 16, issue 8

https://doi.org/10.5194/acp-16-4987-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/acp-16-4987-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 16, issue 8

Research article

|

22 Apr 2016

Research article |

| 22 Apr 2016

Aerosol optical properties in the southeastern United States in summer – Part 1: Hygroscopic growth

Charles A. Brock, Nicholas L. Wagner, Bruce E. Anderson, Alexis R. Attwood, Andreas Beyersdorf, Pedro Campuzano-Jost, Annmarie G. Carlton, Douglas A. Day, Glenn S. Diskin, Timothy D. Gordon, Jose L. Jimenez, Daniel A. Lack, Jin Liao, Milos Z. Markovic, Ann M. Middlebrook, Nga L. Ng, Anne E. Perring, Matthews S. Richardson, Joshua P. Schwarz, Rebecca A. Washenfelder, Andre Welti, Lu Xu, Luke D. Ziemba, and Daniel M. Murphy

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Final revised paper (published on 22 Apr 2016)
Supplement to the final revised paper
Preprint (discussion started on 22 Sep 2015)
Companion paper

Interactive discussion

Status: closed

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

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- Supplement

SC C7507: 'adjust gamma fit', Anne Jefferson, 01 Oct 2015
- AC C12342: 'Response to comment by Anne Jefferson', Charles Brock, 12 Feb 2016
RC C7896: 'anonymous review for "Aerosol hygroscopicity in the southeastern US"', Anonymous Referee #1, 13 Oct 2015
- AC C12344: 'Response to Reviewer #1', Charles Brock, 12 Feb 2016
RC C8554: 'Review of Brock et al., 2015: Aerosol optical properties in the southeastern United States in summer - Part 1: Hygroscopic growth', Anonymous Referee #2, 27 Oct 2015
- AC C12352: 'Response to Reviewer #2', Charles Brock, 12 Feb 2016

Peer-review completion

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

AR by Charles Brock on behalf of the Authors (12 Feb 2016) Manuscript

ED: Referee Nomination & Report Request started (03 Mar 2016) by Andreas Petzold

RR by Anonymous Referee #2 (23 Mar 2016)

Suggestions for revision or reasons for rejection

I like to acknowledge the great effort the authors made to improve the manuscript. To my opinion it substantially improved. Therefore I only have a few minor comments before the final publication:

- Abstract 1: Please define PM and add a space between unit (nm) and number.

- Page 2, line 36 to page 3, line 2: The parameterization from Quinn et al 2005 uses only the mass fraction of sulfate and organic matter therefore is rather imprecise when other aerosol components (e.g. nitrate, ammonia or BC) are present (see Zieger et al., 2015 and figures in the reply to the reviewer). Thus it is important to use all the main components to predict gamma or f(RH). It would be useful to the reader to add this info.

- Page 15, line 3 (conclusions): Please add the particle size for the f(RH)-value (at least for the ammonium sulfate value). Both size and hygroscopicity can have compensating effects, e.g. smaller and less hygroscopic particles (e.g. dominated by organics) can have the same f(RH) as larger and more hygroscopic particles (e.g. sea spray) as shown in Zieger et al., 2010.

References:

Zieger, P., Fierz-Schmidhauser, R., Gysel, M., Ström, J., Henne, S., Yttri, K. E., Baltensperger, U., and Weingartner, E.: Effects of relative humidity on aerosol light scattering in the Arctic, Atmos. Chem. Phys., 10, 3875-3890, doi:10.5194/acp-10-3875-2010, 2010.

Zieger, P., Aalto, P. P., Aaltonen, V., Äijälä, M., Backman, J., Hong, J., Komppula, M., Krejci, R., Laborde, M., Lampilahti, J., de Leeuw, G., Pfüller, A., Rosati, B., Tesche, M., Tunved, P., Väänänen, R., and Petäjä, T.: Low hygroscopic scattering enhancement of boreal aerosol and the implications for a columnar optical closure study, Atmos. Chem. Phys., 15, 7247-7267, doi:10.5194/acp-15-7247-2015, 2015.

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ED: Publish subject to technical corrections (24 Mar 2016) by Andreas Petzold

Dear Chuck,

it's my pleasure to accept your manuscript for publication in ACP after few technical corrections have been included.

These are:
- Abstract 1: Please define PM and add a space between unit (nm) and number.

- Page 2, line 36 to page 3, line 2: The parameterization from Quinn et al 2005 uses only the mass fraction of sulfate and organic matter therefore is rather imprecise when other aerosol components (e.g. nitrate, ammonia or BC) are present (see Zieger et al., 2015 and figures in the reply to the reviewer). Thus it is important to use all the main components to predict gamma or f(RH). It would be useful to the reader to add this info.

- Page 15, line 3 (conclusions): Please add the particle size for the f(RH)-value (at least for the ammonium sulfate value). Both size and hygroscopicity can have compensating effects, e.g. smaller and less hygroscopic particles (e.g. dominated by organics) can have the same f(RH) as larger and more hygroscopic particles (e.g. sea spray) as shown in Zieger et al., 2010.

References:

Zieger, P., Fierz-Schmidhauser, R., Gysel, M., Ström, J., Henne, S., Yttri, K. E., Baltensperger, U., and Weingartner, E.: Effects of relative humidity on aerosol light scattering in the Arctic, Atmos. Chem. Phys., 10, 3875-3890, doi:10.5194/acp-10-3875-2010, 2010.

Zieger, P., Aalto, P. P., Aaltonen, V., Äijälä, M., Backman, J., Hong, J., Komppula, M., Krejci, R., Laborde, M., Lampilahti, J., de Leeuw, G., Pfüller, A., Rosati, B., Tesche, M., Tunved, P., Väänänen, R., and Petäjä, T.: Low hygroscopic scattering enhancement of boreal aerosol and the implications for a columnar optical closure study, Atmos. Chem. Phys., 15, 7247-7267, doi:10.5194/acp-15-7247-2015, 2015.

Best regards

Andreas

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AR by Charles Brock on behalf of the Authors (24 Mar 2016) Manuscript

Short summary

Microscopic pollution particles make the atmosphere look hazy and also cool the earth by sending sunlight back to space. When the air is moist, these particles swell with water and scatter even more sunlight. We showed that particles formed from organic material – which dominates particulate pollution in the southeastern U.S. – does not take up water very effectively, toward the low end of most previous studies. We also found a better way to mathematically describe this swelling process.