Photochemical production of ozone and emissions of NOx and CH4 in the San Joaquin Valley

Trousdell, Justin F.; Caputi, Dani; Smoot, Jeanelle; Conley, Stephen A.; Faloona, Ian C.

doi:https://doi.org/10.5194/acp-19-10697-2019

Articles | Volume 19, issue 16

https://doi.org/10.5194/acp-19-10697-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/acp-19-10697-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 19, issue 16

Research article

|

26 Aug 2019

Research article |

| 26 Aug 2019

Photochemical production of ozone and emissions of NO_x and CH₄ in the San Joaquin Valley

Justin F. Trousdell, Dani Caputi, Jeanelle Smoot, Stephen A. Conley, and Ian C. Faloona

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Final revised paper (published on 26 Aug 2019)
Supplement to the final revised paper
Preprint (discussion started on 23 Jan 2019)
Supplement to the preprint

Interactive discussion

Status: closed

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

- Printer-friendly version

- Supplement

RC1: 'Review', Anonymous Referee #1, 19 Feb 2019
- AC1: 'Response to Referee #1', Justin Trousdell, 12 Mar 2019
  - EC1: 'Corrected version of AC1', Robert McLaren, 24 Apr 2019
RC2: 'review of Trousdell et al.', Anonymous Referee #2, 08 Mar 2019
- EC2: 'Response to Referee 2', Robert McLaren, 24 Apr 2019

Peer-review completion

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

AR by Svenja Lange on behalf of the Authors (25 Apr 2019) Author's response

ED: Referee Nomination & Report Request started (09 May 2019) by Robert McLaren

RR by Anonymous Referee #1 (29 May 2019)

RR by Anonymous Referee #2 (01 Jun 2019)

Suggestions for revision or reasons for rejection

Comments made to manuscript-version5

The authors have answered most of the reviewers’ questions adequately. I have a few more suggestions for this paper before I think it is ready for publication.

I think the Uncertainties section should come earlier in the paper, before the final estimates of emissions are presented. Are the uncertainties, say for the NOx emissions, weighted by the daily uncertainties? In other words, was 182 ± 324 tonnes/d treated the same as 301 ± 166 tonnes/d? I also think the uncertainties should be clearly stated in this section, rather than scattered throughout. I found the boundary layer estimate of 650 ± 50 thrown in a section where it didn’t really fit. A better place for it would be the Uncertainty section. Further, the authors state an uncertainty in the wind measurement of 0.1 m/s. I realize many of the coauthors wrote the original wind measurement paper, but my reading of the stated uncertainty in Conley et al. (2014) as < 0.2 m/s. Did the Mooney aircraft fly an L-pattern during this SJV project? Are the GPS measurements even accurate to 10 cm?

If this paper is going to offload much of the boundary layer analysis to the companion paper, the companion paper should be provided along with this one.

p. 6, line 20, the authors should add the model number of the Picarro, like they did for the Eco Physics instrument.

In section 3.2, Aircraft Instrumentation, please add the estimated uncertainties to these measurements.

Section 4.1.1.2, how does the possible influence of the Soberanes fire compare with your estimate of the footprint? If the fire did affect the measurements, are your footprints too small? And if the fire didn’t affect the measurements, why spend so much time discussing the possible interferences?

p. 21, line 10, what units are 3.6 and 2.4? Are these scaling factors?

Maasakkers et al. (2016) should account for the seasonality of CH4 emissions. How do CH4 emissions in the SJV compare to that work?

Figure 2, you could also refer to Figure 1 for the locations of the cities.

Supplement, p. 3, is this a correction factor that is multiplied by the measured NOx? If so, please add the additional information, e.g., NOx(corrected) = (factor)*NOx(measured)

Grammar Suggestions
p. 2, line 3, change “seem” to “seems”
p. 4, line 7, add a comma after “chemistry”
p. 5, line 11-12, set the clause “coupled … floor” off with commas, and remove the other commas in this sentence
p. 6, line 16 and throughout, “data” should be plural
p. 7, line 21, I’m confused by this statement. The NOAA crew corresponded well with the Mooney crew? Or the ozone measurements agreed well?
p. 7, line 23, change “diagnosis” to “diagnose”
p. 12, line 4, “Results from …” is in boldface
p. 16, line 24, change “in” to “by”
p. 20, line 5, “Data are”
p. 20, line 13, I think d(Cox) should be d(Ox)?
Supplement, p. 2, line 1, subscript the 2 in NO2

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ED: Publish subject to minor revisions (review by editor) (12 Jun 2019) by Robert McLaren

AR by Ian Faloona on behalf of the Authors (02 Jul 2019) Author's response Manuscript

ED: Publish as is (04 Jul 2019) by Robert McLaren

Post-review adjustments

AA: Author's adjustment | EA: Editor approval

AA by Justin Trousdell on behalf of the Authors (13 Aug 2019) Author's adjustment Manuscript

EA: Adjustments approved (19 Aug 2019) by Robert McLaren

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Short summary

We flew a small single-engine instrumented aircraft in a large valley of California to study the factors that determine air pollutant levels in a region of the US that faces serious air quality challenges. After carefully accounting for atmospheric mixing, we found that agriculture is likely a significant and currently underestimated source of nitrogen oxide, a precursor to both ozone and particulate matter pollution and methane, a potent greenhouse gas.