Towards a satellite formaldehyde – in situ hybrid estimate for organic aerosol abundance

Liao, Jin; Hanisco, Thomas F.; Wolfe, Glenn M.; St. Clair, Jason; Jimenez, Jose L.; Campuzano-Jost, Pedro; Nault, Benjamin A.; Fried, Alan; Marais, Eloise A.; Gonzalez Abad, Gonzalo; Chance, Kelly; Jethva, Hiren T.; Ryerson, Thomas B.; Warneke, Carsten; Wisthaler, Armin

doi:https://doi.org/10.5194/acp-19-2765-2019

Articles | Volume 19, issue 5

https://doi.org/10.5194/acp-19-2765-2019

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

https://doi.org/10.5194/acp-19-2765-2019

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

Articles | Volume 19, issue 5

Research article

|

04 Mar 2019

Research article |

| 04 Mar 2019

Towards a satellite formaldehyde – in situ hybrid estimate for organic aerosol abundance

Jin Liao, Thomas F. Hanisco, Glenn M. Wolfe, Jason St. Clair, Jose L. Jimenez, Pedro Campuzano-Jost, Benjamin A. Nault, Alan Fried, Eloise A. Marais, Gonzalo Gonzalez Abad, Kelly Chance, Hiren T. Jethva, Thomas B. Ryerson, Carsten Warneke, and Armin Wisthaler

Download

Final revised paper (published on 04 Mar 2019)
Supplement to the final revised paper
Preprint (discussion started on 27 Aug 2018)
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 of Liao et al.', Anonymous Referee #1, 13 Sep 2018
- AC1: 'Responses to referee#1's comments', Jin Liao, 20 Nov 2018
RC2: 'Review', Anonymous Referee #2, 12 Oct 2018
- AC2: 'Responses to referee#2's comments', Jin Liao, 20 Nov 2018

Peer-review completion

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

AR by Jin Liao on behalf of the Authors (20 Nov 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (26 Nov 2018) by Sally E. Pusede

RR by Anonymous Referee #1 (13 Dec 2018)

Suggestions for revision or reasons for rejection

The manuscript is improved over the original submission, though some aspects of the analysis remain poorly described. I’ve provided suggestions below to address these. Given all the uncertainties and the simplistic application of highly-variable source-specific relationships (lines 364-366 encapsulate the fundamental problem that makes it hard to justify any sort of universal application of slopes), I don’t think that the authors have made a convincing case that this approach is generally worth pursuing, but given the work that went into the analysis, I think that the paper meets the bar for publication (once they have addressed the remaining issues).

1. Lines 105-107: It is unclear what the reader is meant to take from this sentence. Does this approach from de Vries et al. work well for OA? Are there major flaws? Are you trying to provide an alternative approach?

2. Lines 127-128: Jimenez et al. (2009) do not show that OA is a major contributor to AOD (they do not discuss AOD) – an alternate reference is required for this statement.

3. Line 180: state in the text why you convert from STP units

4. Lines 182-189: give measurement details for NO2 for DC3 and CalNex here (you discuss these measurements on lines 429-432). Also need to describe source of isoprene measurements for SEAC4RS.

5. Lines 230-234: also state that using monthly product

6. Lines 260-263: give global emissions of isoprene and NOx used in the model

7. Line 271: mid-level of MERRA-2 surface layer is ~60m, not 140m

8. Line 302: concentrations at STP or under ambient conditions?

9. Lines 305: this is a false statement. Highest PM2.5 levels over the United States are generally in California and in urban regions (see “Our Nation’s Air” report here: https://www.epa.gov/air-trends). Please correct.

10. Figure 1: caption indicates that this shows the data used in this study, but the text indicates that only data < 1km was used. Please modify the figure to show only data below 1 km altitude.

11. Figure 3a: a character is displaying incorrectly on the color bar label.

12. Section 3.1: The authors did not address my concern about the low number of points used to characterize the HCHO:OA from fires. To explicitly address this please add the number of points used for each category/campaign to Table 1 so that this is clear to the reader. Please also add the caveat “though data is limited” at the end of the sentence “…fires during SEAC4RS.” on line 376.

13. Line 432: you state that the NOx range during CalNex was large, but you do not indicate whether the HCHO:OA showed a relationship with NOx in this region. Please address.

14. Section 6.1: why was this analysis performed on the monthly time scale? Would a daily analysis have any benefits? Please discuss.

15. Line 522: you used (NOx)(isoprene) to define the chemical conditions so this is what you should specify here, not “NOx levels” alone.

16. Line 527: specify in text what slope is used for Case 1

17. Line 569: remove “slightly”

18. Line 604: Section 2.6 does not describe what fraction of AOD comes from OA; how was this determination made here?

19. Line 629-630: It should be noted in the text that the “GEOS-Chem simulation” and the “OA estimate” are not independent.

20. Line 640: the authors should briefly explain the four cases in the text to start Section 6.5.

21. Lines 643-645: the authors indicate that they use NO2 observations from OMI data. What is the source of the isoprene concentration data needed to apply the (NOx)(isoprene) chemical characterization in case 2 and 4? Is this from the GEOS-Chem model? If so, some comparison of how well GEOS-Chem reproduces the observed (NOx)(isoprene) during SEAC4RS should be added to the manuscript.

22. Line 780-781: the authors should also indicate that the OA estimate is biased low.

23. The manuscript includes many small grammatical errors and some awkward phrasing; it should be edited for language.

Hide

ED: Publish subject to minor revisions (review by editor) (13 Dec 2018) by Sally E. Pusede

AR by Jin Liao on behalf of the Authors (25 Jan 2019) Author's response Manuscript

ED: Publish subject to technical corrections (05 Feb 2019) by Sally E. Pusede

AR by Jin Liao on behalf of the Authors (06 Feb 2019) Manuscript

Download

Article (5789 KB)
Full-text XML

Short summary

Organic aerosol (OA) intimately links natural and anthropogenic emissions with air quality and climate. Direct OA measurements from space are currently not possible. This paper describes a new method to estimate OA by combining satellite HCHO and in situ OA and HCHO. The OA estimate is validated with the ground network. This new method has a potential for mapping observation-based global OA estimate.