A size-composition resolved aerosol model for simulating the dynamics of externally mixed particles: SCRAM (v 1.0)

Zhu, S.; Sartelet, K. N.; Seigneur, C.

doi:https://doi.org/10.5194/gmd-8-1595-2015

Articles | Volume 8, issue 6

https://doi.org/10.5194/gmd-8-1595-2015

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

https://doi.org/10.5194/gmd-8-1595-2015

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

Articles | Volume 8, issue 6

Model description paper

|

01 Jun 2015

Model description paper |

| 01 Jun 2015

A size-composition resolved aerosol model for simulating the dynamics of externally mixed particles: SCRAM (v 1.0)

S. Zhu, K. N. Sartelet, and C. Seigneur

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Final revised paper (published on 01 Jun 2015)
Preprint (discussion started on 20 Nov 2014)

Interactive discussion

Status: closed

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

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RC C2991: 'Interactive comments on “A size-composition resolved aerosol model for simulating the dynamics of externally mixed particles: SCRAM (V 1.0)” by S. Zhu et al.', Anonymous Referee #1, 20 Jan 2015
- AC C3303: 'Interactive Comment reply to Anonymous Referee 1', Shupeng ZHU, 10 Feb 2015
RC C3042: 'Review comments', Anonymous Referee #2, 21 Jan 2015
- AC C3295: 'Interactive Comment reply to Anonymous Referee 2', Shupeng ZHU, 10 Feb 2015

Peer-review completion

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

AR by Shupeng Zhu on behalf of the Authors (10 Feb 2015) Author's response Manuscript

ED: Referee Nomination & Report Request started (15 Apr 2015) by Gerd A. Folberth

RR by Richard Easter (25 Apr 2015)

Suggestions for revision or reasons for rejection

Comments on revision 1 of “A size-composition resolved aerosol model for simulating the dynamics of externally mixed particles: SCRAM (V 1.0)” by S. Zhu et al.

The authors have clearly put considerable thought and effort into responding to reviewer comments and revising the manuscript. I recommend that the manuscript be accepted for publication after the following minor comments are addressed.

P. 10 L. 288-290. The vapor source units are unusual for a gas, and my original comment was more to clarify whether they prescribed the H2SO4 source or had gas-phase chemistry. So change
“with a sulphuric acid condensation rate of 5.5 μm3 cm−3 per 12 hours (Seigneur et al., 1986; Zhang et al., 1999) (sulphuric acid vapour source of 0.46 μm3 cm−3 290 per hour)”
to
“with constant sulphuric acid vapour source that gives a sulphuric acid condensation rate of 5.5 μm3 cm−3 per 12 hours (Seigneur et al., 1986; Zhang et al., 1999) ”

P. 10 L. 306 and 308, and P. 11 L. 322. Perhaps change the “good” (originally “perfect”) to “excellent”.

P. 12, L. 362. Change “organics originate either from” to “SOA originates either from”, since this does not appear to involve POA, which is emitted.

P. 12 L. 387-388. Change
“fraction of one chemical component is high (between 0.8 and 1), while the mass fraction of the other chemical components is low”
to
“fraction of one chemical component group is high (between 0.8 and 1), while the mass fractions of the other chemical component groups are low”

P. 13 L. 392-393. Change
“additional composition sections for the last group should be added to the current composition list without any modification to the main structure of the program”
to
“additional composition sections for the last group could be added to the current composition list without any modification to the main structure of the SCRAM code”

P. 13 L. 407. Change
“nucleation was not activated during”
to
“no nucleation occurred during”

P. 13 L. 415-417. Revise somewhat to address:
> Aren’t the CI 12 and CI 14 emissions mixed?
> Are there emissions of condensable organic vapors that produce SOA?

P. 14 L. 424-427. Change to something like
“Figure 8 shows that mixed CI 15 particles that were emitted into the third size section migrated to the fourth size section, and this could result from coagulation between CI 14 size section 4 particles with either CI 3 or CI 14 size section 3 particles, or between two CI 14 size section 3 particles.”

P. 14 L. 429-430. Change
“(exact mass fraction of dominate group will be specific within the parentheses right after the group name here after)”
to
“(the exact mass fraction of the dominant group will be specified within the parentheses right after the group name here after)”

P. 15 L. 469-472. The discussion here could be clearer about how well the size distributions of individual species masses agree or differ under internally- and externally-mixed assumptions. So change
“The number and the species mass distributions are also similar, although external mixing leads to slightly lower ammonium concentrations (2.68 μg m−3 versus 2.70 μgm−3), slightly higher nitrate concentrations (3.19 μg m−3 versus 3.03 μg m−3) and higher chloride concentrations (0.36 μg m−3 versus 0.25 μg m−3).”
to something like
“The bulk mass concentrations of individual species are also similar, although external mixing leads to slightly lower ammonium concentrations (2.68 μg m−3 versus 2.70 μgm−3), slightly higher nitrate concentrations (3.19 μg m−3 versus 3.03 μg m−3) and higher chloride concentrations (0.36 μg m−3 versus 0.25 μg m−3). The size distributions for number and for individual species masses are also quite similar in the internal and external mixing simulations.”
Substitute appropriate wording for “quite similar” in the second sentence.

P. 17 L. 547. Change
“offer more detail”
To
“provide details”
Delete the “more” because the internally mixed simulations provide no details at all about mixing state within a size section.

P. 17 L. 555-559. The intent of the second sentence in this paragraph was somewhat unclear to me, so please rephrase it. Clearly identifying the particular features for the readers requires careful wording. If I interpreted this correctly, then something like the following might be better:
“Assuming bulk equilibrium when solving condensation/evaporation leads to different size and composition distributions than the dynamic approach under both the internally- and externally-mixed assumptions. With the bulk equilibrium approach, internally- and externally-mixed assumptions lead to similar average compositions as a function of size, and unmixed particles remain under the externally-mixed assumption, which were both observed with the dynamic C/E approach.”

Fig. 2. In legend, change “mean N fractions” to “mean, N sections”, where N is 2, 10, or 100. Similar for the “std N sections”.

Fig. 8 and 10.
> Change vertical axes labels from mass to number.
> The numbering on the vertical axes is somewhat cryptic (“1, 2, 3, 4, 5” along the axes and the “1e10” at top left corner of each plot) and should be improved. Also, why not use #/cm3 units as in Figs. 1 and 3?

Fig. 7, 8, 9, and 10.
> The font size is quite small, and will likely be too small if figure size is reduced somewhat during publication. I suggest increasing font size by about 50%.
> The legend at the top of each figure is also quite small. I suggest using 2 rows with 6 boxes each, so that the individual boxes can be twice their current size.
These changes could also benefit presentations on SCRAM.

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ED: Publish subject to minor revisions (Editor review) (27 Apr 2015) by Gerd A. Folberth

AR by Shupeng Zhu on behalf of the Authors (30 Apr 2015) Author's response Manuscript

ED: Publish as is (05 May 2015) by Gerd A. Folberth

AR by Shupeng Zhu on behalf of the Authors (07 May 2015)

Short summary

This article presents the Size-Composition Resolved Aerosol Model (SCRAM) for simulating the dynamics of externally mixed atmospheric particles. The model is first validated by comparison with a reference solution and with results of simulations using internally mixed particles. Then, the importance of representing the mixing state when modelling atmospheric aerosol concentrations is investigated in a box model simulation using data representative of air pollution in Greater Paris.