The role of semi-volatile organic compounds in the mesoscale evolution of biomass burning aerosol: a modeling case study of the 2010 mega-fire event in Russia

Konovalov, I. B.; Beekmann, M.; Berezin, E. V.; Petetin, H.; Mielonen, T.; Kuznetsova, I. N.; Andreae, M. O.

doi:https://doi.org/10.5194/acp-15-13269-2015

Articles | Volume 15, issue 23

https://doi.org/10.5194/acp-15-13269-2015

© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/acp-15-13269-2015

© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 15, issue 23

Research article

|

01 Dec 2015

Research article |

| 01 Dec 2015

The role of semi-volatile organic compounds in the mesoscale evolution of biomass burning aerosol: a modeling case study of the 2010 mega-fire event in Russia

I. B. Konovalov, M. Beekmann, E. V. Berezin, H. Petetin, T. Mielonen, I. N. Kuznetsova, and M. O. Andreae

Download

Final revised paper (published on 01 Dec 2015)
Preprint (discussion started on 26 Mar 2015)

Interactive discussion

Status: closed

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

- Printer-friendly version

- Supplement

RC C2232: 'Review for The role of semi-volatile organic compounds in the mesoscale evolution of biomass burning aerosol', Anonymous Referee #1, 05 May 2015
- AC C5446: 'Authors' response to the comments of the anonymous referee # 1', Igor Konovalov, 30 Jul 2015
RC C3298: 'Review of Konovalov', Anonymous Referee #2, 07 Jun 2015
- AC C5456: 'Authors' response to the comments of the anonymous referee # 2', Igor Konovalov, 30 Jul 2015

Peer-review completion

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

AR by Igor Konovalov on behalf of the Authors (04 Aug 2015) Author's response Manuscript

ED: Referee Nomination & Report Request started (13 Oct 2015) by Kostas Tsigaridis

RR by Anonymous Referee #1 (05 Nov 2015)

Suggestions for revision or reasons for rejection

Review of Kovonalov et al. 2015.
The authors have made substantial revisions compared to their previously submitted version. I feel that the revised version is substantially improved, and the results are important to be published. Overall it was a pleasure reading this revised version of the manuscript.
However, I still have a few questions/comments which need clarifications.
I therefore, recommend the manuscript for minor revisions, and it could be accepted for publication after these comments are addressed.

1. Equation 1: Is beta(OC) total gas+particle or Ctot? That’s what it seems based on their equation 1, since the first term on the RHS,”fi” is a factor applied to Ctot and the 2nd term on their RHS essentially calculates particle fraction Xp(for example see Shrivastava et al. 2006 cited in this paper). But beta(POA) is just particle phase OA, COA. The authors need to clarify this in the description of equation 1.

2. Line 380 and below: The authors imply beta(OC) has been frequently measured in lab and field studies for biomass burning. Do they mean Ctot(gas+particle ) OC is measured? This could be the case since measurements are made at dilution ~10 which represent mostly the initial cooling and increase of PM mass . But again this point needs clarification.

3. Line 395 and below: The authors assumed that all POA are released into atmosphere as particles. But what’s their assumed size distribution of these particle emissions? What measurements is it based on?

4. Line 445 and below: Note that May et al. 2013 did not provide data for IVOCs because they didn’t measure them. It’s not primarily because BB emits less IVOC than motor vehicles. Please rephrase. Also note that just after 1 generation of oxidation the IVOCs may be transformed to the SVOC range so I do not fully agree with the note that IVOCs do not contribute significantly to SOA for biomass burning.

5. Line 715: Emission factor for OC, BC, CO, NOx and NMHC were specified using an updated dataset. There is a reference for M.O.Andrea unpublished data. Are these emission factors globally applicable? Are these derived by averaging a large number of studies? Note that averaging a large number of high and low emission factors does not capture the variability of fuel and combustion-specific biomass burning emissions. Since this is unpublished, some more information is needed about their applicability.

6. Lines below 960, 2nd column on page 10: The authors note that VBS-3 scenario is based on the modified oxidation scheme by Grieshop et al. 2009, which involves representations of fragmentation and condensed-phase processes. But the representations of fragmentation and condensed phase processes are based on Shrivastava et al. 2013,2015. Please correct the reference.

7. Line 1200 and below towards the end of page 12: Authors mention that photolysis rates can be attenuated by BB, hampering NEMR in the central part of plume. Have the authors checked that this is the case or is it just a speculation? Regardless, I recommend providing a map of OH (oxidant concentrations) to clarify this point maybe in the supporting information.

8. Paragraph at the beginning of page 13: I understand it’s difficult to exactly remove background effects for calculations of delta PM or delta CO. The author’s calculations neglect temporal variations of background, especially considering that fires were major influence on variability of simulated profiles of species. Note that fires themselves influence background conditions. Please acknowledge these difficulties in calculations of background.

9. Paragraphs on line 1285 and below: Note that Shrivastav et al. 2013, 2015 saw large differences due to condensed phase NVSOA formation at locations farther away from the plume since COA is reduced in plume outflow during transport and dilution, and that favored evaporation of SVSOA. But in the author’s study the small differences between SVSOA and NVSOA are expected, since they are looking at a much smaller transport distances compared to Shrivastava et al. 2015. In addition, ambient temperature also affects differences between SVSOA and NVSOA. What was the average surface temperature in their study domain?

10. Last line of the first paragraph on page 17, around line 1645: The sentence is ambiguous: Therefore, adequacy of representation of SOA formation in a concrete model needs to be carefully evaluated (see e.g. Shrivastav et al. 2015) prior to using that model for estimating BB aerosol emissions. I assume the authors agree that Shrivastava et al. 2015 compared their model predictions with a suite of surface, aircraft and ground measurements. But a quick look at their sentence could also mean Shrivastava et al. 2015 did not adequately evaluate their model. I understand the authors did not mean to be critical of Shrivastava et al. 2015, but they should clarify this sentence.

11. First paragraph on the second column of line 17: The authors note: “In our case systematic model errors may be associated, in particular, with a simplified representation of the fragmentation process”. I find this note to be only partially true. More importantly, model errors are due to the parameters of the fragmentation process e.g. branching ration between functionalization and fragmentation and also uncertainties in the SIVOC emissions. A simple fragmentation scheme (suggested by Shrivastava et al. 2013, 2015 and implemented by the authors) is not necessarily that problematic, since it offers the benefit of a small number of tunable parameters that can be fit to measurements. Suggest rephrasing this sentence accordingly.

Hide

ED: Reconsider after minor revisions (Editor review) (10 Nov 2015) by Kostas Tsigaridis

AR by Igor Konovalov on behalf of the Authors (12 Nov 2015) Author's response Manuscript

ED: Publish as is (13 Nov 2015) by Kostas Tsigaridis

AR by Igor Konovalov on behalf of the Authors (13 Nov 2015)

Short summary

(1) The mesoscale evolution of aerosol from open biomass burning (BB) has been successfully simulated using the volatility basis set (VBS) framework. (2) The simulations disregarding semivolatile nature of organic compounds forming BB aerosol are found to be inconsistent with measurements in the region and period affected by the Russian 2010 wildfires. (3) The VBS method enables one to improve the consistency of "top-down" and "bottom-up" estimates of BB aerosol emissions.