There is an excellent proposal entitled A Proposed Test Suite for Atmospheric Model Dynamical Cores by Christaine Jablonowski of the University of Michigan which Climate Science was alerted to from a February 3 2008 weblog on Climate Audit.
The idea for this test is described as
“Tests of atmospheric General Circulation Models (GCMs) and, in particular, tests of their dynamical cores are important steps towards future model improvements. They reveal the influence of an individual model design on climate and weather simulations and indicate whether the circulation is described representatively by the numerical approach.
Testing a global 3D atmospheric model is not straightforward. In the absence of non-trivial analytic solutions, the model evaluations most commonly rely on intuition, experience and model intercomparisons. In addition, GCM simulation statistics are typically compared to global reanalysis data while numerical weather forecasts are compared to local observations. Such approaches are not applicable to pure dynamical core assessments that isolate the dynamics package from the physical parameterizations. In general, three different sets of equations are most commonly used in dynamical cores. These include the hydrostatic primitive equations as well as the non-hydrostatic shallow-atmosphere and non-hydrostatic deep-atmosphere equation sets. As modeling groups now move towards the next generation of dynamical cores a standard test suite for hydrostatic and non-hydrostatic dynamics packages on the sphere if highly desirable. This webpage contributes to this effort. It suggests a collection of dynamical core test cases with varying complexity.”
Such evaluations of the global models used to make multi-decadal climate predictions are long overdue. In the paper
Pielke, R.A., 1991: Overlooked scientific issues in assessing hypothesized greenhouse gas warming. Environ. Software, 6, 100-107, I wrote
“The horizontal grid spacing of general circulation models is around 400 km. As shown by Pielke [the first edition of Pielke, 2002], as least four grid increments are required to reasonably represent an atmospheric feature, thus this grid resolution would only permit features 1600 km or larger to be reasonably represented in the models, Since extratropical cyclones often are observed to have horizontal wavelengths as small as 500 km or so, they are poorly represented in these models, Since these features provide the major physical mechanism for the exchange of heat, moisture, and momentum between the subtropics and the polar regions, the inability of GCM representations to adequately represent these exchanges is a serious shortcoming. Tropical cyclones, which also provide an important mechanism for exchanges between the tropics and higher latitude is even more poorly represented since its scales of important physical processes includes the eye wall which can be tens of kilometers in radial size.”
and
“Upwelling of deep, cold ocean waters occurs at a number of locations around the world including the equatorial Pacific, around Antarctica, and off the west coast of North America, northern South America, northwest Africa, southwest Africa, and elsewhere. Caused by the direction and speed of the wind at the ocean surface, these upwelled regions of cold surface waters usually have an extent in one spatial direction of 50km or so. Since atmosphere-ocean GCMs have spatial resolutions on the order of 400km, these important sinks for carbon dioxide are ignored.”
The test of the dynamical core fits into these evaluations and assessment of the global climate models as prediction tools. As a necessary condition, when configured to run in a multi-decadal predictive mode they should still be used to make short-term global weather predictions in order to asses their skill at simulating the development and movement of major high and low pressure systems, including tropical cyclones. Moreover, they should be run as seasonal weather predictions using inserted sea surface temperatures at the initial time in order to see if they can skillfully predict the development of El Nino and La Nina events, as well as other circulation patterns such as the North Atlantic Oscillation. If they cannot accurately predict these short term and seasonal weather patterns, they should not believed as valid and societally useful prediction tools on the regional (and even the global average) scale decades into the future.