Closing the water balance with cosmic-ray soil moisture measurements  and assessing their relation to evapotranspiration in two semiarid  watersheds

Schreiner-McGraw, A. P.; Vivoni, E. R.; Mascaro, G.; Franz, T. E.

doi:https://doi.org/10.5194/hess-20-329-2016

Articles | Volume 20, issue 1

https://doi.org/10.5194/hess-20-329-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/hess-20-329-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 20, issue 1

Research article

|

19 Jan 2016

Research article |

| 19 Jan 2016

Closing the water balance with cosmic-ray soil moisture measurements and assessing their relation to evapotranspiration in two semiarid watersheds

A. P. Schreiner-McGraw, E. R. Vivoni, G. Mascaro, and T. E. Franz

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Final revised paper (published on 19 Jan 2016)
Preprint (discussion started on 10 Jun 2015)

Interactive discussion

Status: closed

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

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RC C2336: 'Review of the manuscript “Closing the Water Balance with Cosmic-ray Soil Moisture Measurements and Assessing Their Spatial Variability within Two Semiarid Watersheds” by Adam P. Schreiner-McGraw et al.', Anonymous Referee #1, 01 Jul 2015
- AC C4050: 'Response to Reviewer 1 Comments', Enrique R. Vivoni, 05 Oct 2015
RC C2356: '"Closing the water balance with cosmic-ray soil moisture measurements and assessing their spatial variability within two semiarid watersheds” by: A. P. Schreiner-McGraw, E. R. Vivoni, G. Mascaro, and T. E. Franz', Anonymous Referee #2, 02 Jul 2015
- AC C4072: 'Response to Reviewer 2', Enrique R. Vivoni, 05 Oct 2015
EC C2480: 'Start interacting', Nunzio Romano, 09 Jul 2015
RC C2918: 'Review comments (Closing the Water Balance with Cosmic-ray Soil Moisture Measurements and Assessing Their Spatial Variability within Two Semiarid Watersheds)', Anonymous Referee #3, 30 Jul 2015
- AC C4082: 'Response to Reviewer 3 Comments', Enrique R. Vivoni, 05 Oct 2015
AC C4089: 'Revised Manuscript without Track Changes (PDF)', Enrique R. Vivoni, 05 Oct 2015
AC C4090: 'Revised Submission with Track Changes (PDF)', Enrique R. Vivoni, 05 Oct 2015

Peer-review completion

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

ED: Reconsider after major revisions (13 Oct 2015) by Nunzio Romano

AR by Enrique R. Vivoni on behalf of the Authors (13 Oct 2015) Author's response Manuscript

ED: Referee Nomination & Report Request started (16 Oct 2015) by Nunzio Romano

RR by Heye Bogena (16 Oct 2015)

RR by Anonymous Referee #4 (20 Oct 2015)

Suggestions for revision or reasons for rejection

Schreiner-McGraw et al 2015
Closing the Water Balance with Cosmic-ray Soil Moisture Measurements and Assessing Their Relation to Evapotranspiration in Two Semiarid Watersheds
In this study the soil moisture dynamics of two watersheds in Arizona and New Mexico were analysed. CRNS observation were validated through comparison with distributed sensors. CRNS observations were also compared to water balance estimates of soil moisture with some interesting findings. While there have been other validation type papers there are some new approaches applied in this paper that make it a valid contribution to the body of CRNS literature. I am not sure that the title entirely captures the papers contribution. It might be worth revisiting since your major restructuring efforts.
I have read the paper and the response to previous reviews and am satisfied that the authors have addressed all the required issues. There still seems to be some confusion around the applicability of the Desilets equation in an unmodified sense to volumetric soil moisture contents. Other authors have applied bulk density modifications which could have easily been applied here and which would then align the analysis more directly with the z* calculations. The correct application of techniques needs to be clarified in the CRNS literature.
The restructuring has help to clarify the paper contributions and I see no major impediments to publication. I think this paper is well suited to publication in HESS. Comments of 3 previous reviewers have resulted in major improvements to this paper I can find no major flaws which will inhibit publications.
Minor comments
P4L8: “…which is often used…”
P5L3: sentence starting on the line does not make sense, overlapping with the footprint of what?
P5L7: “…each instrumented...”
P5L19: suggest delete after “scale”, sentence is unwieldy
P9L21: This equation is for gravimetric soil moisture not volumetric. Just need to say it is adjusted to include bulk density for achieving volumetric.
P11L4: Admittedly the hydrogen contributions from lattice water, biomass and soil carbon will be small and can probably be ignored in your case but I don’t think the statement that they are implicitly accounted for in the calibration procedure is true (this may mislead others in different environments). The Desilets curve is for pure sand with no other hydrogen sources other than soil water. The effect I am talking about is shown in Zreda et al 2012 Fig 6 and associated text. If you are using your own calibration fit to observations and not fitting to Desilets then this can be ignored.
P16L8: rearrange sentence as it is grammatically incorrect
P17L2: illustrative of what?
P22L1: abbreviate to CRNS
P24L4: Last sentence need to be rewritten as it makes no sense.

Figures: In general, some of the line colors are hard to differentiate (e.g. Fig 3, 9) . Can distinct colors be used?
References
Zreda, M., W. J. Shuttleworth, X. Zeng, C. Zweck, D. Desilets, T. Franz, and R. Rosolem (2012), COSMOS: the COsmic-ray Soil Moisture Observing System, Hydrol. Earth Syst. Sci., 16(11), 4079-4099, doi: 10.5194/hess-16-4079-2012.

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RR by Anonymous Referee #2 (26 Oct 2015)

RR by Anonymous Referee #3 (18 Nov 2015)

Suggestions for revision or reasons for rejection

The work presented by Schreiner-McGraw et al. evaluates the soil moisture dynamics measured by cosmic-ray sensors (CRS), in comparison to sensor networks (SN), at two semi-arid sites. The authors exploit the use of CRS and SN in a simple water balance model as well as employing empirical relationships to understand the role of spatial variability in soil moisture and evapotranspiration.

This manuscript has been improved considerably. The authors have re-organized the structure of the paper so it now appears more clear to readers. In addition, I am very satisfied with author’s explanation on the assumptions and simplifications when using the N0 equation without explicitly accounting for the lattice water (while later clearly explained why lattice water is needed when calculating z*). They have justified the land cover characteristics of the SRER based on previous studies (although I still keep my comment that Figure 2 in the new version does not support that - notice yellow patches for SRER and lack of those in EC tower footprint, similarly notice purple patches for JER and lack of those in EC tower footprint).

Finally, I suggest the authors to modify the following sentence:
“To our knowledge, soil moisture estimates from the CRNS technique have not been used to study the hydrological processes occurring in small watersheds overlapping with the measurement footprint or for improving the parameterization of land surface models.”

To
“To our knowledge, soil moisture estimates from the CRNS technique have only been recently used to study the hydrological processes occurring in small watersheds overlapping with the measurement footprint or for improving the parameterization of land surface models (Shuttleworth et al., 2013; Rosolem et al. 2014).”

Rosolem, R., Hoar, T., Arellano, A., Anderson, J. L., Shuttleworth, W. J., Zeng, X., and Franz, T. E. (2014) Translating aboveground cosmic-ray neutron intensity to high-frequency soil moisture profiles at sub-kilometer scale, Hydrol. Earth Syst. Sci., 18, 4363-4379, doi:10.5194/hess-18- 4363-2014, 2014.

Shuttleworth, W. J., Rosolem, R., M. Zreda, and T. Franz (2013): The COsmic-ray Soil Moisture Interaction Code (COSMIC) for Use in Data Assimilation, Hydrology and Earth System Sciences, 17, 3205-3217, doi:10.5194/hess-17-3205-2013.

Therefore, I can recommend this paper to be published after taking into account the small details mentioned above.

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ED: Publish subject to minor revisions (Editor review) (07 Dec 2015) by Nunzio Romano

AR by Enrique R. Vivoni on behalf of the Authors (09 Dec 2015) Author's response Manuscript

ED: Publish as is (20 Dec 2015) by Nunzio Romano

AR by Enrique R. Vivoni on behalf of the Authors (29 Dec 2015)

Short summary

Soil moisture estimates from a novel method were evaluated in two semiarid watersheds. We found good agreements between the technique and estimates derived from watershed instruments designed to close the water balance. We then investigated local hydrologic processes and link between evapotranspiration and soil moisture obtained from the novel measurements.