Journal cover Journal topic
Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
Geosci. Model Dev., 9, 3655-3670, 2016
https://doi.org/10.5194/gmd-9-3655-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
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. Hewitt1, Malcolm J. Roberts1, Pat Hyder1, Tim Graham1, Jamie Rae1, Stephen E. Belcher1, Romain Bourdallé-Badie2, Dan Copsey1, Andrew Coward3, Catherine Guiavarch1, Chris Harris1, Richard Hill1, Joël J.-M. Hirschi3, Gurvan Madec3,4, Matthew S. Mizielinski1, Erica Neininger1, Adrian L. New3, Jean-Christophe Rioual1, Bablu Sinha3, David Storkey1, Ann Shelly1,a, Livia Thorpe1, and Richard A. Wood1 1Met Office, Exeter, UK
2Mercator Océan, Toulouse, France
3National Oceanography Centre, Southampton, UK
4IPSL, Paris, France
anow at: Cumulus, City Financial Investment Company Limited, London EC4R 1EB, UK
Abstract. There is mounting evidence that resolving mesoscale eddies and western boundary currents as well as topographically controlled flows can play an important role in air–sea interaction associated with vertical and lateral transports of heat and salt. Here we describe the development of the Met Office Global Coupled Model version 2 (GC2) with increased resolution relative to the standard model: the ocean resolution is increased from 1/4 to 1/12° (28 to 9 km at the Equator), the atmosphere resolution increased from 60 km (N216) to 25 km (N512) and the coupling period reduced from 3 hourly to hourly. The technical developments that were required to build a version of the model at higher resolution are described as well as results from a 20-year simulation. The results demonstrate the key role played by the enhanced resolution of the ocean model: reduced sea surface temperature (SST) biases, improved ocean heat transports, deeper and stronger overturning circulation and a stronger Antarctic Circumpolar Current. Our results suggest that the improvements seen here require high resolution in both atmosphere and ocean components as well as high-frequency coupling. These results add to the body of evidence suggesting that ocean resolution is an important consideration when developing coupled models for weather and climate applications.

Citation: Hewitt, H. T., Roberts, M. J., Hyder, P., Graham, T., Rae, J., Belcher, S. E., Bourdallé-Badie, R., Copsey, D., Coward, A., Guiavarch, C., Harris, C., Hill, R., Hirschi, J. J.-M., Madec, G., Mizielinski, M. S., Neininger, E., New, A. L., Rioual, J.-C., Sinha, B., Storkey, D., Shelly, A., Thorpe, L., and Wood, R. A.: 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, Geosci. Model Dev., 9, 3655-3670, https://doi.org/10.5194/gmd-9-3655-2016, 2016.
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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.
We examine the impact in a coupled model of increasing atmosphere and ocean horizontal...
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