Articles | Volume 29, issue 23
https://doi.org/10.5194/hess-29-6917-2025
© Author(s) 2025. This work is distributed under the Creative Commons Attribution 4.0 License.
Global observations of land-atmosphere interactions during flash drought
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- Final revised paper (published on 02 Dec 2025)
- Supplement to the final revised paper
- Preprint (discussion started on 08 Apr 2025)
- Supplement to the preprint
Interactive discussion
Status: closed
Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor
| : Report abuse
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RC1: 'Comment on egusphere-2025-1489', Anonymous Referee #1, 17 May 2025
- AC1: 'Reply on RC1', Bethan Harris, 11 Jul 2025
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RC2: 'Comment on egusphere-2025-1489', Anonymous Referee #2, 04 Jun 2025
- AC1: 'Reply on RC1', Bethan Harris, 11 Jul 2025
Peer review completion
AR – Author's response | RR – Referee report | ED – Editor decision | EF – Editorial file upload
ED: Publish subject to revisions (further review by editor and referees) (13 Aug 2025) by Rohini Kumar
AR by Bethan Harris on behalf of the Authors (15 Aug 2025)
Author's response
Author's tracked changes
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ED: Referee Nomination & Report Request started (15 Aug 2025) by Rohini Kumar
RR by Anonymous Referee #2 (04 Sep 2025)
ED: Publish as is (16 Sep 2025) by Rohini Kumar
AR by Bethan Harris on behalf of the Authors (17 Sep 2025)
The study investigates the land-atmosphere interactions during flash droughts using daily satellite products from 2000 to 2020 for the purpose of improving the S2S predictability of flash drought. The flash drought events are identified using surface soil moisture (ESA CCI Soil moisture combined active/passive microwave product) and land-atmosphere coupling processes for composites of flash drought events are analysed using standardised anomaly of net radiation at the surface from CERES, latent heat flux from GLEAM and sensible heat flux as the difference between land surface temperature (ESA CCI) and 2m air temperature (ERA5). The study demonstrates that flash droughts with stronger land-atmosphere coupling persistent surface energy budget perturbations months before and after onset. Further, the study shows that increased sensible heat flux during flash droughts feeds back to raise near-surface air temperatures, especially in semi-arid African regions.
The manuscript is generally well-written with comprehensive details on assumptions and limitations of the data. The study provides detailed investigation of land and near-surface atmospheric variables during the flash drought; however, the current work lacks substantial conclusions with respect to knowledge gaps in S2S predictability. I think the paper could be strengthened with additional investigations on evolution of variables modulating land-atmosphere interaction for other land cover classes (shown in Figure 2) in addition to rainfed croplands.
Therefore, I recommend major revisions before publication to enhance the robustness and significance of the findings.
Specific Comments:
Figure 2: Provide clarification on the timing of the drought event in the figure caption and discussion. The figure S2 mention the composites during peak growing season even though it is shown as accompanying figure of Figure 2.
Figure S3: The wind speed at 10m shows substantial difference for different quartile, which suggests wind speed is important for the sensible heat anomaly. The authors should add relevant discussion for the validity of sensible heat flux calculation in section 3.2.
Line 161-162: Can authors add more clarification on how DT is calculated at 0.01° spatial resolution? What is the spatial resolution of ERA5 2m used in the study?
Line 169-171: Provide clarity on ERA5 2m wind speed. How is it calculated?
Line 206-209: The negative latent heat flux anomaly for shrubland before the onset of flash drought has been explained as transiting to water limitation regime earlier than other land covers. However, the evolution of surface soil moisture is similar for all land cover classes. There should be other factor that may explain the early negative latent heat flux anomaly. I suggest investigating the evolution of variables for shrublands as done for rainfed cropland in Figure 3.
Line 303-305: Please rephrase for clarity or provide additional details on the regions.
Line 310-311: The three semi-arid regions have different land cover classes. I think land cover should be brought into the discussion as there is difference in the evolution of land-atmospheric coupling process for different land cover classes (Figure 2).
Line 351-355: These sentences suggests that study lacks substantial conclusion as per the objective set in the introduction. I suggest discussing the role of different land cover classes for non-robust relationship between precursor variable and 2m anomalies. Further, the role of VOD as precursor need to be assessed for other key regions to have robust conclusion.
Line 403: If VOD is closely linked to root zone soil moisture (RZSM) and serves as a precursor for 2m temperature anomalies during flash droughts, does identifying flash droughts based solely on surface soil moisture provide a reliable approach for flash drought monitoring? Further, I suggest using ESA-CCI-COM based root zone soil moisture dataset in addition to GLEAM RZSM and discuss its application for land atmosphere interaction during flash drought.