LISA: a lightweight stratospheric air sampler

Hooghiem, Joram J. D.; de Vries, Marcel; Been, Henk A.; Heikkinen, Pauli; Kivi, Rigel; Chen, Huilin

doi:https://doi.org/10.5194/amt-11-6785-2018

Articles | Volume 11, issue 12

https://doi.org/10.5194/amt-11-6785-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

The 10th International Carbon Dioxide Conference (ICDC10)...

https://doi.org/10.5194/amt-11-6785-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 11, issue 12

Research article

|

20 Dec 2018

Research article |

| 20 Dec 2018

LISA: a lightweight stratospheric air sampler

Joram J. D. Hooghiem, Marcel de Vries, Henk A. Been, Pauli Heikkinen, Rigel Kivi, and Huilin Chen

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Final revised paper (published on 20 Dec 2018)
Preprint (discussion started on 26 Jan 2018)

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'Review of Hooghiem et al.', Anonymous Referee #1, 28 Feb 2018
- AC1: 'Reply to interactive comment by Referee #1', Joram Hooghiem, 13 Jul 2018
RC2: 'Comment for "LISA: a lightweight stratospheric air sampler"', Anonymous Referee #2, 15 Mar 2018
- AC2: 'Reply to interactive comment by Referee #2', Joram Hooghiem, 13 Jul 2018

Peer-review completion

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

AR by Joram Hooghiem on behalf of the Authors (13 Aug 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (16 Aug 2018) by Markus Leuenberger

RR by Anonymous Referee #1 (17 Aug 2018)

Suggestions for revision or reasons for rejection

Additional review of Hooghiem et al.,

The authors have answered most of the issues brought forward during the review process. The calculation of the contamination in section 6.4., however, still seems to be odd and in my view is flawed.

The argumentation before eq. 6 is clearly wrong. The majority of the molecules in the sample bag are not introduced via diffusion (you would need a very long sampling time) but by whole air flux.

Second, I cannot follow the argumentation that all the contamination is explained by diffusion, either. Small leaks in the system would also allow for introduction of a contamination, which would not be driven by diffusion.

Third, I cannot follow the mathematical argumentation. If a diffusive flux into the sample bag or out of the bag is calculated (eq. 8 and 9) a concentration gradient is required (not a concentration). Eq. 8 and 9 are in my view not correct and also do not yield fluxes, simply when looking at the units. Then in eq. 9 the differences between the two fluxes is used to derive a bias in mixing ratio. This is again physically not correct (the difference of two fluxes would be a flux). Mixing ratios and fluxes are again mixed up in eq. 10-12.

Then again, the step from (15) to (16) does not seem to involve the usage of (8) and (9) as stated but rather is based on (13) and (14).

In my view, equation 16 is correct, but does not require any argumentation about molecular diffusion, but can simply be derived from 13 and 14. In fact, if it is to be derived based on assumptions about molecular diffusion, then the diffusion coefficients of the different isotopes would need to be considered. The fraction fc which is then needed in (16) can simply be estimated as explained in my first review from mass balance argumantation. This would then yield very similar results as found in the revised manuscript. The way it is derived in the revised manuscript is, however, in my view, not correct. I think that arguing just by assuming that it must be a contamination from mixing with air of different origin and thus applying mass balance equations is much simpler and sufficient for such an estimation.

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RR by Anonymous Referee #2 (30 Aug 2018)

ED: Reconsider after major revisions (06 Sep 2018) by Markus Leuenberger

AR by Joram Hooghiem on behalf of the Authors (17 Oct 2018) Author's response Manuscript

ED: Publish subject to technical corrections (06 Nov 2018) by Markus Leuenberger

AR by Joram Hooghiem on behalf of the Authors (12 Nov 2018) Manuscript

Short summary

We have developed a lightweight stratospheric air sampler, named LISA, for measurements of CO₂, CH₄ and CO mole fractions. The LISA sampler is capable of grabbing stratospheric air samples at an altitude of up to 30 km and provides a useful tool for routine stratospheric measurements of both mole fractions and isotopic composition of trace gases.