Deconstruction of tropospheric chemical reactivity using aircraft measurements: the Atmospheric Tomography Mission (ATom) data

Prather, Michael J.; Guo, Hao; Zhu, Xin

doi:https://doi.org/10.5194/essd-15-3299-2023

Articles | Volume 15, issue 7

https://doi.org/10.5194/essd-15-3299-2023

© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/essd-15-3299-2023

© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 15, issue 7

Data description paper

|

31 Jul 2023

Data description paper |

| 31 Jul 2023

Deconstruction of tropospheric chemical reactivity using aircraft measurements: the Atmospheric Tomography Mission (ATom) data

Michael J. Prather, Hao Guo, and Xin Zhu

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Final revised paper (published on 31 Jul 2023)
Preprint (discussion started on 14 Apr 2023)

Interactive discussion

Status: closed

RC1:
'Review of essd-2023-110', Anonymous Referee #1, 07 Jun 2023

This paper presents a detailed description and analysis of observation-derived results from the ATom aircraft experiment, which covers the remote troposphere of the Pacific and Atlantic basins during 4 seasons. Using global chemical transport models constrained by the comprehensive ATom data sets, ozone production and loss rates, as well as methane and carbon monoxide (CO) loss rates, have been determined and are presented and analyzed in this paper. This work provides extensive documentation of these results and discusses the photochemical environment of the remote troposphere around the globe. Recommendations are also provided for using the results for global model evaluation. These results will be valuable for future users of the ATom data and the presented derived results. The discussion and extensive figures will be helpful for users.
I recommend publication after considering the following point.
In Section 3.3 average profiles are presented. The averages over the complete Pacific and Atlantic basins (averaging all latitudes between 53S and 60N) do not seem particularly useful, as that includes averages of opposite seasons in the 2 hemispheres (Figures 29, 30, etc.; also Figures 40-43). The comparisons of the 3 tropical basins is interesting. I would leave out the Pacific and Atlantic plots, or separate the results shown in them by hemisphere.
Abstract - l.10: Artic -> Arctic
l.98 - city of Christchurch is one word.

Citation: https://doi.org/10.5194/essd-2023-110-RC1
- AC1:
  'Thanks and response to RC1 with a query', Michael Prather, 07 Jun 2023
  
  First, thank you very much for reviewing this long and detailed manuscript. I greatly appreciate your time and catching of the typos. The major issue raised was regarding the Pacific & Atlantic basin average profiles/PDFs for the reactivities (Section 3.3, Figs 29-32 & Section 3.4 Figs 40-43). I am willing to pull theses figures and the discussion of them, but feel that they do provide some useful information. Admittedly the major production/loss terms shift north and south seasonally as shown in the 2D curtain plots of the individual profiling. Yet, most of the reactivity in each basin is contained in the 53S-60N range. Thus the single profiles give a basin-wide average. So for Fig 29(P-O3 Pacific), we find that the seasonality across ATom-234 does not affect the mean, but that ATom-1 has unusally low P-O3, but for the Atlantic it is ATom-3 that has a much higher average. I agree that use of these profiles to examine the seasonality of the basin-wide averages NEEDS to be better written up and explained in Section 3.3.
  Reviewer #1, please respond if you can. Would a better explanation of the values of these figures suffice? Averaging over the seasonality of each deployment seems to be a different way to look at the data.
  
  Citation: https://doi.org/10.5194/essd-2023-110-AC1
  - RC3: 'Reply on AC1', Anonymous Referee #1, 08 Jun 2023
    
    The proposed additional text in AC3 is helpful, and with its inclusion in the paper I agree the paper is appropriate for publication.
    
    Citation: https://doi.org/10.5194/essd-2023-110-RC3
RC2:
'Comment on essd-2023-110', Anonymous Referee #2, 07 Jun 2023

Prather et al. extend their analyses and discussion of the data collected during the NASA ATom campaigns with their present manuscript. This is an incredibly unique publication. I did wonder if this contains too much interesting science for a "Data description paper" but it does match the brief, so to say, in providing an overhwelmingly thorough description of the ATom data -- from the perspective of chemical reactivity.

This is an incredibly verbose but very useful contribution to the atmospheric chemistry community and I recommend publication following my very minor corrections ontop of those already identified by reviewer 1.
Technical corrections in addition to those from reviewer 1:

In several places (e.g., Line 107, Fig Captions 40-47; 62-64, and the Data Availability section) the text reads "Atom" where it should read "ATom". Please correct.

Citation: https://doi.org/10.5194/essd-2023-110-RC2
- AC2: 'Response to Reviewer #2', Michael Prather, 07 Jun 2023
  
  'Atom' indeed, mea culpa, thanks for the careful read. Apologies for the verbosity, but ESSD provided me with the opportunity to present the entire data set - including some analysis - without tucking bits and pieces into a supplement. Thank you Earth System Science Data.
  
  Citation: https://doi.org/10.5194/essd-2023-110-AC2
AC3: 'Final Revisions to essd-2023-110', Michael Prather, 07 Jun 2023

We have corrected all the identified typos and propose to keep all the figures (inclduing mean profiles) but add the following paragraph to the beginning of Section 3.3:
3.3 Mean altitude profiles
Given the inherent synoptic variability plus the large seasonal shifts in chemical reactivity across the Pacific and Atlantic basins seen in the individual profiles (Figures 6-13), one might ask how useful or representative the four ATom transects are for testing model statistics. Because the 53°S-60°N Pacific and Atlantic transects contain the north-south seasonal shifts and most of the reactivity (see Southern Ocean, Arctic and Antarctic reactivities above), a mean profile should average over some of the synoptic variability and give us a seasonal variation in the basin-mean reactivity that could test chemistry-climate models. Seasonal variability in the mean reactivity profiles is clearly due to shifts in the chemical composition caused, for example, in the Atlantic by the cycle of African biomass burning and convection. A similar reasoning applies to basin-wide probability densities, see Section 3.4 below.

We hope this addition satisfies the reviewers and editor, and we are now ready to move forward with publication.

Citation: https://doi.org/10.5194/essd-2023-110-AC3

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload

AR by Michael Prather on behalf of the Authors (23 Jun 2023) Author's response Author's tracked changes Manuscript

ED: Publish as is (26 Jun 2023) by Luis Millan

AR by Michael Prather on behalf of the Authors (29 Jun 2023)

Short summary

The Atmospheric Tomography Mission (ATom) measured the chemical composition in air parcels from 0–12 km altitude on 2 km horizontal by 80 m vertical scales for four seasons, resolving most scales of chemical heterogeneity. ATom is one of the first missions designed to calculate the chemical evolution of each parcel, providing semi-global diurnal budgets for ozone and methane. Observations covered the remote troposphere: Pacific and Atlantic Ocean basins, Southern Ocean, Arctic basin, Antarctica.