Water vapor density and turbulent fluxes from three generations of infrared gas analyzers

Kutikoff, Seth; Lin, Xiaomao; Evett, Steven R.; Gowda, Prasanna; Brauer, David; Moorhead, Jerry; Marek, Gary; Colaizzi, Paul; Aiken, Robert; Xu, Liukang; Owensby, Clenton

doi:https://doi.org/10.5194/amt-14-1253-2021

Articles | Volume 14, issue 2

https://doi.org/10.5194/amt-14-1253-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/amt-14-1253-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 14, issue 2

Research article

|

18 Feb 2021

Research article |

| 18 Feb 2021

Water vapor density and turbulent fluxes from three generations of infrared gas analyzers

Seth Kutikoff, Xiaomao Lin, Steven R. Evett, Prasanna Gowda, David Brauer, Jerry Moorhead, Gary Marek, Paul Colaizzi, Robert Aiken, Liukang Xu, and Clenton Owensby

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Final revised paper (published on 18 Feb 2021)
Preprint (discussion started on 27 Aug 2020)

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'Reviewer comments', Anonymous Referee #1, 11 Sep 2020
- AC1: 'Point-by-point Responses to Referee 1 for # amt-2020-302', Xiaomao Lin, 14 Oct 2020
RC2: 'Three generations of infrared gas analyzers', Anonymous Referee #2, 12 Sep 2020
- AC2: 'Point-by-point Responses to Referee #2 for # amt-2020-302', Xiaomao Lin, 14 Oct 2020

Peer-review completion

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

AR by Xiaomao Lin on behalf of the Authors (23 Oct 2020) Manuscript

ED: Referee Nomination & Report Request started (07 Nov 2020) by Jun Wang

RR by Anonymous Referee #1 (14 Nov 2020)

Suggestions for revision or reasons for rejection

Here I review the revision of “Water vapor density and turbulent fluxes from three generations of infrared gas analyzers”.

While the manuscript is generally improved, there are several instances where the advice of the reviewers is discarded and I think it should be considered prior to publication (or the publication should move elsewhere).

My comments use the line numbers of the author response version.

Major comments:
1. The authors ignore the suggestion to discuss transducer shadow effect (which could be introduced in the paragraph L100, and elsewhere). Doing so will heighten a sense of the work’s relevance and move it from an instrument comparison to a flux comparison. Take some of the response from L967+ and put it into the text.
2. The authors should comment on potential impact on CO2 flux via the WPL correction if not the CO2 flux differences themselves. This is an important implication of this work
3. The authors do not sufficiently highlight their assumptions around rmsd, which are that (1) they implicitly consider the 7500RS as the “good value” and deviation from it as “Bad” even though the article also highlights periods where the 7500RS seems to suffer measurement drift in comparison to the other sensor types (L301). It’s better to be clearer that there is no gold-standard and you are assessing differences among sensors and not differences from a standard.
4. The reference to upper and lower values is still unclear (L186-8) and feels heuristic or arbitrary.
5. The description of advection can still be made clearer, and also its effect on the energy balance closure.
6. Fig 2 could be improved by increasing the marker size in the legend; the points there are too small for me to detect the difference in blues and greens. (particularly Li-7500 and HMP155S)
7. R1 MC2 the energy balance term discussion (L992-7) is not clear and could be still added to Fig 7. It won’t confuse the reader to have additional, helpful information there. (see also the point made in response to R1MC3)
8. R1MC5 state explicitly that there is the potential appearance of a conflict of interest but it was managed by the means described in the response (L1020).
9. R1 minor comment 2, “following rainfall events” – I disagree that this duration should not be quantified. Add “for periods from one to a few days” or something similar.

Minor comments :
1. L 20 this suggestion was intended to then remove the words “water vapor density fluctuations” from L22, please don’t repeat this phrase.
2. L309-310 did they see loss in signal strength (RSSI or ADC) during this period?
3. L375 add apostrophe-s after IRGA
4. L445 the transition from general results to one specific half hour seems abrupt. Perhaps adding “for example” and improving the transition would be helpful.
5. L448 and 449 shift case from singular (was) to plural (were). Pick one and re-write
6. L467 “exactly” is too precise. Rephrase.

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ED: Reconsider after major revisions (27 Nov 2020) by Jun Wang

AR by Xiaomao Lin on behalf of the Authors (06 Jan 2021) Author's response Author's tracked changes Manuscript

ED: Publish as is (17 Jan 2021) by Jun Wang

AR by Xiaomao Lin on behalf of the Authors (18 Jan 2021)

Short summary

Fast-response infrared gas sensors have been used over 3 decades for long-term monitoring of water vapor fluxes. As optically improved infrared gas sensors are newly employed, we evaluated the performance of water vapor density and water vapor flux from three generations of infrared gas sensors in Bushland, Texas, USA. From our experiments, fluxes from the old sensors were best representative of evapotranspiration based on a world-class lysimeter reference measurement.