Km-scale regional coupled system in the Northwest European shelf for weather and climate applications: RCS-UKC4

Berthou, Ségolène; Castillo, Juan Manuel; Fraser-Leonhardt, Vivian; Mahmood, Sana; Makrygianni, Nefeli; Arnold, Alex; Sanchez, Claudio; Lewis, Huw W.; Partridge, Dale; Best, Martin; Bricheno, Lucy; Davies, Helen; Clark, Douglas B.; Clark, James R.; Polton, Jeff A.; Saulter, Andrew; Short, Chris J.; Tinker, Jonathan; Tucker, Simon; Wright, Maisie

doi:10.5194/gmd-19-8535-2026

Articles | Volume 19, issue 18

https://doi.org/10.5194/gmd-19-8535-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/gmd-19-8535-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 19, issue 18

Model description paper

|

15 Sep 2026

Model description paper |

| 15 Sep 2026

Km-scale regional coupled system in the Northwest European shelf for weather and climate applications: RCS-UKC4

Ségolène Berthou, Juan Manuel Castillo, Vivian Fraser-Leonhardt, Sana Mahmood, Nefeli Makrygianni, Alex Arnold, Claudio Sanchez, Huw W. Lewis, Dale Partridge, Martin Best, Lucy Bricheno, Helen Davies, Douglas B. Clark, James R. Clark, Jeff A. Polton, Andrew Saulter, Chris J. Short, Jonathan Tinker, Simon Tucker, and Maisie Wright

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Final revised paper (published on 15 Sep 2026)
Preprint (discussion started on 20 Jan 2026)

Interactive discussion

Status: closed

RC1:
'Comment on egusphere-2025-6216', Anonymous Referee #1, 14 Apr 2026

Please see the attached file.

Citation: https://doi.org/10.5194/egusphere-2025-6216-RC1
- AC1: 'Reply on RC1', Segolene Berthou, 27 Jul 2026
  
  We thank Reviewer 1 for taking time to read our manuscript and for their useful suggestions, which we have addressed in the attached file.
  
  Citation: https://doi.org/10.5194/egusphere-2025-6216-AC1
RC2:
'Comment on egusphere-2025-6216', Anonymous Referee #2, 18 Jun 2026

The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2026/egusphere-2025-6216/egusphere-2025-6216-RC2-supplement.pdf

Citation: https://doi.org/10.5194/egusphere-2025-6216-RC2
- AC2: 'Reply on RC2', Segolene Berthou, 27 Jul 2026
  
  We thank reviewer 2 for the time spent on our manuscript and the useful comments which helped to greatly improve the manuscript.
  
  Citation: https://doi.org/10.5194/egusphere-2025-6216-AC2

Peer review completion

AR – Author's response | RR – Referee report | ED – Editor decision | EF – Editorial file upload

AR by Segolene Berthou on behalf of the Authors (29 Jul 2026) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (10 Aug 2026) by Lele Shu

RR by Anonymous Referee #2 (22 Aug 2026)

RR by Anonymous Referee #1 (23 Aug 2026)

Suggestions for revision or reasons for rejection

Second-round review of “Km-scale regional coupled system in the Northwest European shelf for weather and climate applications: RCS-UKC4”

In the revised manuscript, the authors have responded carefully to most of my previous comments. In particular, the discussion of Proudman resonance has been appropriately qualified, the inconsistency in the ocean time step has been corrected, the NSE description has been revised, and most figure-related issues have been addressed. I recommend minor revision. The following points should be addressed before publication:
1. The attribution of the improved wave RMSE has been appropriately softened in the main text (around Lines 375-378). However, the Abstract still states that the improved wave forecast skill “is attributed to a good representation of tidal current/wave/wind interactions.” This remains stronger than supported by the experimental design. Please make the Abstract consistent with the more cautious wording in the main text, for example by stating that the improvement “may partly reflect” these interactions, together with differences in resolution and scientific configuration.
2. Around Lines 214-217, the manuscript states that RAL3.3 “gives a good total radiative budget,” although no direct heat-budget measurements were available. This remains somewhat stronger than the evidence permits. Please consider wording such as “is consistent with improved surface fluxes” and explicitly identify this as an indirect inference based on SST.
3. The caption of Figure 5 refers to “ERA5 (= HadISST).” ERA5 and HadISST are distinct products, so this notation is potentially misleading. Please clarify.
4. The caption of Figure 12 states “Same as Fig. 10 for wind speed.” This should presumably be “Same as Fig. 11 for wind speed,” while retaining the statement that the buoy locations are shown in Figure 10. In addition, the Figure 13 caption describes the shading as “one standard deviation from the mean ensemble bias”; it appears that the shading instead represents one standard deviation around the ensemble mean. Please check and revise.
5. The colour and line-style information has now been added to Figure 22, as requested. For clarity and consistency, “plain line” should be replaced by “solid line,” and the duplicated full stop at the end of the caption should be removed.
6. A final language and consistency check is still needed. Examples include “in the Northwest European shelf” in the title, “iacross” around Line 314, “The the wave growth parameter” around Line 466, duplicated punctuation around Lines 679 and 739, subject-verb disagreement in “Developments ... provides” around Line 680, and “Please visit Please visit” around Line 748. Please also standardize “min” rather than “mn” and use “near-real-time” when it functions as a compound modifier.

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ED: Publish as is (25 Aug 2026) by Lele Shu

AR by Segolene Berthou on behalf of the Authors (03 Sep 2026) Manuscript

Short summary

The UK’s new RCS-UKC4 (Regional Coupled Suite – UK Coupled domain version 4) system combines atmosphere, ocean, waves, land, rivers, and biogeochemistry models to improve coastal weather and climate predictions. It offers better storm wave predictions, more accurate river flows, and captures rapid sea-level changes. These advances help predict multiple hazards more reliably, supporting safer communities and helping better planning.