Icebergs in the ocean. Photo by Simon Maennling

Ocean and ice model development

Improving and evaluating the performance of the ocean and sea ice components of global climate models.

Ocean and sea-ice models are the primary tool for research carried out by the climate, cryosphere and oceans group. The model development team is responsible for developing ocean models, in collaboration with the Nucleus for European Modelling of the Ocean (NEMO) consortium and the Community Ice Code (CICE) sea-ice model based at Los Alamos National Laboratory. The group's role is to develop and improve the global configurations that are used at the Met Office. These are run both in ocean-ice forced mode using the DFS4 (Bordeau et al., 2010) and as part of the global climate configuration of the Met Office climate prediction model: HadGEM3 family coupled climate model. They are also used within the Met Office seasonal prediction system: GloSea5 seasonal forecasting and short-range Ocean Forecasting Research systems. Assessment and evaluation of the models against current and past climate is an important part this group's work.

The requirement for high resolution climate models means that it is no longer practical to maintain ocean and sea ice components which have a geographic North Pole. The grid convergence of a regular latitude-longitude grid requires not just filtering to maintain stability but also the insertion of a polar island. The approach that has been taken is to introduce new ocean and sea ice components that are formulated with generalised orthogonal coordinates and are therefore able to employ a tripolar grid as shown by the figure above (Murray, 1996).

Key aims

  • To provide the ocean and sea-ice components of the Met Office climate models.

  • To improve representation of physical processes in the ocean and sea ice across a range of time and spatial scales.

  • To evaluate the ocean and sea ice models against observed climate data in order to understand the causes of errors in the model climate and reduce these errors.

Current projects

  • Ongoing development and assessment of the NEMO (ocean) and CICE (sea-ice) models for the HadGEM3 coupled climate model.

  • Metric development for assessing the performance of the ocean and sea-ice models.

  • Coupling an ocean model to the numerical weather prediction configuration of the Met Office Unified Model to improve extended-range forecasting.

  • Testing the parametrization of the surface boundary layer in NEMO.

  • Understanding the processes driving Arctic sea-ice changes on a range of timescales and assessing the model's representation of these.

  • Identifying leading order processes which may impact on future predictions of Arctic sea-ice cover.

References

  • Bordeau, G., B. Barnier, A-M, Treguier, T. Penduff, S. Gulev (2010), An ERA40-based atmospheric forcing for global ocean circulation models. Ocean Modelling, vol. 31, p88-104.

  • Murray, R. J. (1996), Explicit generation of orthogonal grids for ocean models. Journal of Computational Physics, vol. 126, p251-273.