Testing water fluxes and storage from two hydrology configurations within the ORCHIDEE land surface model across US semi-arid sites

MacBean, Natasha; Scott, Russell L.; Biederman, Joel A.; Ottlé, Catherine; Vuichard, Nicolas; Ducharne, Agnès; Kolb, Thomas; Dore, Sabina; Litvak, Marcy; Moore, David J. P.

doi:https://doi.org/10.5194/hess-24-5203-2020

Articles | Volume 24, issue 11

https://doi.org/10.5194/hess-24-5203-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/hess-24-5203-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 24, issue 11

Research article

|

10 Nov 2020

Research article |

| 10 Nov 2020

Testing water fluxes and storage from two hydrology configurations within the ORCHIDEE land surface model across US semi-arid sites

Natasha MacBean, Russell L. Scott, Joel A. Biederman, Catherine Ottlé, Nicolas Vuichard, Agnès Ducharne, Thomas Kolb, Sabina Dore, Marcy Litvak, and David J. P. Moore

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Final revised paper (published on 10 Nov 2020)
Supplement to the final revised paper
Preprint (discussion started on 04 Dec 2019)
Supplement to the preprint

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'Review of "Multi-variable, multi-configuration testing of ORCHIDEE land surface model water flux and storage estimates across semi-arid sites in the southwestern US"', Anonymous Referee #1, 20 Dec 2019
- SC1: 'Informal initial response to Anonymous Reviewer #1', Natasha MacBean, 17 Feb 2020
- AC1: 'Formal response to Reviewer 1', Natasha MacBean, 09 Apr 2020
RC2: 'Review of "Multi-variable, multi-configuration testing of ORCHIDEE land surface model water flux and storage estimates across semi-arid sites in the southwestern US"', Anonymous Referee #2, 10 Feb 2020
- SC2: 'Informal initial response to anonymous reviewer #1', Natasha MacBean, 17 Feb 2020
  - SC3: 'Informal initial response to anonymous reviewer #2', Natasha MacBean, 17 Feb 2020
    - RC3: 'Reply to informal initial response', Anonymous Referee #2, 20 Feb 2020
      - AC3: 'Response to Informal Response from Reviewer 2', Natasha MacBean, 09 Apr 2020
- AC2: 'Formal response to Reviewer 2', Natasha MacBean, 09 Apr 2020

Peer-review completion

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

ED: Publish subject to revisions (further review by editor and referees) (24 Apr 2020) by Anke Hildebrandt

AR by Natasha MacBean on behalf of the Authors (28 Apr 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (20 May 2020) by Anke Hildebrandt

RR by Anonymous Referee #2 (18 Jun 2020)

RR by Anonymous Referee #1 (17 Jul 2020)

Suggestions for revision or reasons for rejection

Comments on revision of MacBean et al. for HESS.

The authors surely answered to all the questions raised by the reviewers. I have to admit that I was a bit overwhelmed (and a bit annoyed) with the amount of text: 58 pages rebuttal letter vs 27 pages of paper text. Sorry if I could not gather every little detail in the paper and in the letter.

So the only thing that I would still like to be changed is the explanation of the tiling in the 11-layer version (see below). I find it essential to understand the implications of the manuscript but the model structure is not clear to me from the text. While the text explains well the vertical structure within the soil column, it is not explaining well the tiling, the different vegetated and non-vegetated fractions. There are so many fractions that I got lost. Perhaps the word "sub-fraction" could be used sometimes.

l. 246ff (of the track changes version): sorry I could not understand the logic even that there is a formula. What are soil tiles? And what does it mean that all PFTs are gathered in one tile? Are they sharing the same soil? Are they all tapping into the same soil? How do you check that you do not take too much water from it?

I have understood: one grid cell, say 10 km x10 km, is divided into fractions with different PFTs, say 2 PFTs, Temperate broadleaf deciduous tree (f_v1) and C4 grass (f_v2). Is there always another fraction Bare soil (f_b) so that f_v1+f_v2+f_b=1 or is it simply f_v1+f_v2=1? Each PFT fraction has its own bare soil sub-fraction (f_b1 and f_b2) calculated with a fraction of vegetation cover, often denoted f_c. I would not call this not a modified Beer-Lambert equation because k_ext is not an extinction coefficient. f_c is rather a gap probability taking into account only between-trees gap probability (and not within-tree gap probability). I would then write directly f_cj = 1-exp(-LAI_j) or fb_j = f_vj * exp(-LAI_j). Is there then only one soil underneath the vegetated and bare soil part of this PFT fraction? Are they acting on the same soil water? Or are there two soils, one for vegetated and one for bare soil? If so, how do you preserve water if LAI changes?

So I find the formulation in the paper misleading that there is E and T from a vegetated surface. It is rather how the bare soil fraction is defined, on which only E happens whereas only T happens over the effectively vegetated surface. The difference is indeed the energy input to the surface. Bare soil gets direct sunlight and will have hence much higher surface temperatures than the soil below a canopy. So in this respect, it did not change between the 2- and 11-layer versions. It is rather how the bare soil fraction is defined that changed.

But this might be wrong because you might use only one surface temperature per PFT fraction. Then what is calculated is actually not a bare soil fraction but a below-canopy E assuming a direct connection between above- and below canopy, i.e. no canopy air space.

As you might have understood by now, I could really not understand how all the tiling is done and the real assumptions in the 11-layer version. I looked into the reference of Guimberteau et al. (2014) but that did not help. I did not look into all the Rosnay papers. And I think that the water fluxes cannot be understood without explaining how heat is calculated. I find it essential, though, to understand tiling and the relation between energy and water for this paper because this is so fundamental for semi-arid regions. Perhaps, the authors could do a renewed effort to explain it better in the manuscript.

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ED: Publish subject to minor revisions (review by editor) (27 Jul 2020) by Anke Hildebrandt

AR by Natasha MacBean on behalf of the Authors (07 Aug 2020) Author's response Manuscript

ED: Publish subject to minor revisions (review by editor) (01 Sep 2020) by Anke Hildebrandt

AR by Natasha MacBean on behalf of the Authors (01 Sep 2020) Author's response Manuscript

ED: Publish as is (24 Sep 2020) by Anke Hildebrandt