Three dimensional test problems for global atmospheric models
There are a wide range of idealised tests available in 1 or 2 dimensions for testing atmospheric code but only limited 3 dimensional tests. The dynamical core tests of Held and Suarez need to be run for several hundred days to approach quasi-equilibrium. Full 3 dimensional balanced flows can be easily set up on an f-plane in limited area models where the lateral boundaries can be used to maintain a constant (in time) large scale flow. Here I will describe a similar approach for global tests where the flow is close to geostrophic and hydrostatic balance when orography is absent. Orography can be introduced inducing perturbations to the flow which increase with either the size of the orography or the speed of the flow. These tests are 3 dimensional analogues to some of the shallow-water test set and are useful in testing dynamics algorithms and the response to orographic forcing. The tests need to be run for no more than 10 days to provide meaningful results making them ideal for testing at high resolution.