ENDGame

Professor John Thuburn and Dr Iva Kavcic

ENDGame stands for Even Newer Dynamics for General atmospheric modelling of the environment. It is the name of a new weather and climate prediction model dynamical core being developed by the Met Office Dynamics Research group. ENDGame resembles the current operational Met Office model in using a semi-implicit semi-Lagrangian discretization on a latitude-longitude C-grid and a height-based vertical coordinate.

However, it aims to improve in several ways: the use of a conservative semi-Lagrangian scheme for mass and tracer transport, the use of a more fully implicit time scheme based on an iterative solver providing better stability, accuracy and robustness, and the consistent inclusion of several switchable options for the geometry and dynamical approximations.

For around 10 years, John Thuburn has been collaborating with the Dynamics Research group, particularly on the design of ENDGame. His contributions to the project have included:

  • showing how to improve the accuracy of Rossby waves; these are slowly propagating but meteorologically important atmospheric waves;
  • improved understanding of the coupling of a conservative semi-Lagrangian mass transport scheme with a semi-implicit time integration scheme;
  • improved understanding of the convergence properties of the iterative solver and its relation to the overall stability of the scheme.

Under a NERC-funded project, Iva Kavcic is devloping a version of ENDGame based on a Lagrangian vertical coordinate, that is, the model's grid levels move vertically with the flow. The new version will be used to test the hypothesis that Lagrangian conservation properties, and other related properties such as the budgets of entropy and unavailable energy, are better handled with a Lagrangian vertical coordinate than a height-based one. The formulation of the Lagrangian-coordinate dynamical core is kept as close as possible to that of the height-based-coordinate dynamical core, so that the comparison is as clean as possible.

 Relative vorticity field from a simulation of barotropic instability (the Galewsky et al. test) using the ENDGame shallow-water model.
 Surface potential temperature field from an idealized dry climate simulation (the Held Suarez test) using the three-dimensional ENDGame dynamical core.Note how the model is able to capture the sharp gradients that form without the need for any explicit dissipation terms to maintain stability.
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