Developing a drought-monitoring index for the contiguous US using SMAP

Sadri, Sara; Wood, Eric F.; Pan, Ming

doi:https://doi.org/10.5194/hess-22-6611-2018

Articles | Volume 22, issue 12

https://doi.org/10.5194/hess-22-6611-2018

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

https://doi.org/10.5194/hess-22-6611-2018

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

Articles | Volume 22, issue 12

Research article

|

21 Dec 2018

Research article |

| 21 Dec 2018

Developing a drought-monitoring index for the contiguous US using SMAP

Sara Sadri, Eric F. Wood, and Ming Pan

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Final revised paper (published on 21 Dec 2018)
Preprint (discussion started on 16 Apr 2018)

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'Review from Sadri et al. SMAP-based drought monitoring index', Anonymous Referee #1, 18 May 2018
- AC1: 'Response to Referee 1', Sara Sadri, 10 Sep 2018
RC2: 'Review of “A SMAP-based drought monitoring index for the Unites States”', Anonymous Referee #2, 25 Jul 2018
- AC2: 'Response to Referee 2', Sara Sadri, 10 Sep 2018

Peer-review completion

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

ED: Reconsider after major revisions (further review by editor and referees) (16 Sep 2018) by Nunzio Romano

AR by Sara Sadri on behalf of the Authors (17 Sep 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (06 Oct 2018) by Nunzio Romano

RR by John S Kimball (19 Oct 2018)

Suggestions for revision or reasons for rejection

This paper represents a revised version of a previous manuscript submission. I have reviewed the revised paper and the authors have adequately addressed the prior reviewer comments, which have been incorporated into the latest manuscript revision. The manuscript is now suitable for publication and should be of wide interest to the community. However, there are several technical and grammatical issues summarized below, which should be addressed at the authors discretion prior to final publication.

Section 2.1, p. 5: Clarify what product version of the SMAP SPL3SMP data is used here. In the latest SMAP product release (R16) frozen ground or snow covered areas are masked out using a combined NPR and single channel algorithm based freeze-thaw retrieval, rather than just NPR (Line 10). The NPR is predominantly used at high latitudes where there’s a larger V-H Tb difference and sufficient NPR signal-noise, whereas the single channel algorithm is predominantly used at lower temperate latitudes and over vegetated areas.

p. 5, Ln 23 (grammar): “…without the discontinuous data..” should be “…without discontinuous data restrictions due to gaps in the SPL3SMP soil moisture retrievals”.

p. 7, Ln 7 (grammar): ”..of beta..” should be “.. of the beta..”.

p. 8, Figure 2 caption (grammar): “..bottom row: as the ..” should be “..bottom row: same as the…”.

p. 11, Ln 24: Include Lawston et al. 2017. GRL reference here to justify suspect irrigated lands impact on SMAP soil moisture retreivals. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017GL075733

Results discussion of Figure 5: Can the authors provide a potential reason for the low warm season correspondence in the PNW region? I would also expect to see more of a pattern of low correspondence over the major mountain areas (e.g. Rockies, Sierra-Cascades) given the coarse SMAP Tb footprint, but this isn’t very apparent; can the authors talk to this as well?

Results discussion of Figure 6: Can the authors include additional explanation of the low warm season correspondence in the great lakes region? I suspect this may be due to contamination of SMAP Tb and soil moisture retrievals from small water bodies, since the soil moisture algorithm.

Figure 6-7 captions: Clarify what the black x symbols are in the SPL3SMP maps.

p. 16 bottom (sentence structure): “..SMAP to offer index..” should be “..SMAP index to offer..” .

p. 17 bottom (sentence structure): “Our index SPL3SMP index produc maps…” should be “Our SPL3SMP index maps…”.

p. 17 bottom: More information and clarification is needed regarding use of the GRACE NDMC product for the 2017 period. The NDMC product is a model data assimilation product that combines GRACE data with other meteorological information. In 2017 the GRACE sensor was failing and the resulting water storage observations were unreliable. As such, the last GRACE gravity field retrievals and RL06 reprocessing only go through June 2017 and Aug 2016, respectively. Figure 9 and the associated results and discussion therefore likely don’t reflect actual GRACE observations for 2017.

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RR by Anonymous Referee #1 (12 Nov 2018)

ED: Publish subject to minor revisions (review by editor) (18 Nov 2018) by Nunzio Romano

AR by Sara Sadri on behalf of the Authors (20 Nov 2018) Author's response Manuscript

ED: Publish as is (07 Dec 2018) by Nunzio Romano

AR by Sara Sadri on behalf of the Authors (08 Dec 2018)

Short summary

Of particular interest to NASA's SMAP-based agricultural applications is a monitoring product that assesses near-surface soil moisture in terms of probability percentiles for dry and wet conditions. However, the short SMAP record length poses a statistical challenge for the meaningful assessment of its indices. This study presents initial insights about using SMAP Level 3 and Level 4 for monitoring drought and pluvial regions with a first application over the contiguous United States (CONUS).