The impact of resolving the Rossby radius at mid-latitudes in the ocean:
results from a high-resolution version of the Met Office GC2 coupled model

Hewitt, Helene T.; Roberts, Malcolm J.; Hyder, Pat; Graham, Tim; Rae, Jamie; Belcher, Stephen E.; Bourdallé-Badie, Romain; Copsey, Dan; Coward, Andrew; Guiavarch, Catherine; Harris, Chris; Hill, Richard; Hirschi, Joël J.-M.; Madec, Gurvan; Mizielinski, Matthew S.; Neininger, Erica; New, Adrian L.; Rioual, Jean-Christophe; Sinha, Bablu; Storkey, David; Shelly, Ann; Thorpe, Livia; Wood, Richard A.

doi:https://doi.org/10.5194/gmd-9-3655-2016

Articles | Volume 9, issue 10

https://doi.org/10.5194/gmd-9-3655-2016

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

Special issue:

Nucleus for European Modelling of the Ocean - NEMO

https://doi.org/10.5194/gmd-9-3655-2016

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

Articles | Volume 9, issue 10

Model description paper

|

13 Oct 2016

Model description paper |

| 13 Oct 2016

The impact of resolving the Rossby radius at mid-latitudes in the ocean: results from a high-resolution version of the Met Office GC2 coupled model

Helene T. Hewitt, Malcolm J. Roberts, Pat Hyder, Tim Graham, Jamie Rae, Stephen E. Belcher, Romain Bourdallé-Badie, Dan Copsey, Andrew Coward, Catherine Guiavarch, Chris Harris, Richard Hill, Joël J.-M. Hirschi, Gurvan Madec, Matthew S. Mizielinski, Erica Neininger, Adrian L. New, Jean-Christophe Rioual, Bablu Sinha, David Storkey, Ann Shelly, Livia Thorpe, and Richard A. Wood

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Final revised paper (published on 13 Oct 2016)
Preprint (discussion started on 19 Apr 2016)

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'review', Stephen M. Griffies, 29 Apr 2016
- AC1: 'Response', Helene Hewitt, 09 Jul 2016
RC2: 'Review', Andy Hogg, 21 May 2016
- AC2: 'Response', Helene Hewitt, 09 Jul 2016
AC3: 'Manuscript with tracked changes', Helene Hewitt, 09 Jul 2016

Peer-review completion

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

AR by Helene Hewitt on behalf of the Authors (11 Jul 2016) Author's response Manuscript

ED: Referee Nomination & Report Request started (27 Jul 2016) by R. Marsh

RR by Andy Hogg (06 Aug 2016)

Suggestions for revision or reasons for rejection

The reviewers have, for the most part, made modifications which satisfy my comments. I have a couple of outstanding issues that I would like to raise:

- The ACC transport section remains confused. Firstly, I don’t think it’s accurate to say that the GC2-N512O12 experiment has increased ACC transport — the point being that it decreases by less than the ORCA025 cases during the short simulation. In additions, Jones is not a great reference here, because their main point is that: "due to the slow adjustment timescale of the density structure, it is difficult to detect these changes using existing observations from the past few decade” (quoting from their conclusions). I suggest rewriting this paragraph again, and stressing that while each simulation decreases during the 20 year simulation, the O12 case decreases the least, and noting the possible reasons. In highlighting those reasons, it might be useful to analyse whether density has changed more on the Southern side (influenced by Weddell Sea convection) or the northern side (presumably due to the wind stress) between each case. In addition, when noting the different wind trends it would help to be more quantitative about how much the winds have changed.

- Thankyou for adding a comment about the magnitude of biases being lower in the North Atlantic and larger in the Southern Ocean. Please also add an approximate number for the Southern Ocean SST bias — how much greater is it than before?

Finally, I accept that these runs were computationally expensive and that it is now too late to save the information on the density space overturning. My suggestion is to add this diagnostic as a standard output option for future releases of the model. The code to do this is freely available in MOM. If these diagnostics can be calculated online then you will never again be asked by a reviewer to provide that information!

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ED: Publish subject to minor revisions (Editor review) (31 Aug 2016) by R. Marsh

AR by Helene Hewitt on behalf of the Authors (20 Sep 2016) Author's response Manuscript

ED: Publish as is (25 Sep 2016) by R. Marsh

AR by Helene Hewitt on behalf of the Authors (26 Sep 2016)

Short summary

We examine the impact in a coupled model of increasing atmosphere and ocean horizontal resolution and the frequency of coupling between the atmosphere and ocean. We demonstrate that increasing the ocean resolution from 1/4 degree to 1/12 degree has a major impact on ocean circulation and global heat transports. The results add to the body of evidence suggesting that ocean resolution is an important consideration when developing coupled models for weather and climate applications.