Schaer Test Case

 

The Schaer test case is described in two references - Schaer et al, 2002: A New Terrain-Following Vertical Coordinate Formulation for Atmospheric Prediction Models. Monthly Weather Review, Vol. 130, 2459-2480; Klemp et al, 2003: Numerical Consistency of Metric Terms in Terrain-Following Coordinates.  Monthly Weather Review, Vol. 131, 1229-1239.  The Schaer et al (2002) reference presents results from a  number of different test cases (the results for the test case below can be found on pages 2475-2477).  The Klemp et al (2003) paper deals exclusively with this test and presents the analytical solution for the test along with an extensive discussion of model design issues related to this test.  A detailed discussion of this test as it relates to semi-Lagrangian models is given in Girard et al 2005: Finescale Topography and the MC2 Dynamics Kernel, Monthy Weather Review, Vol 133, 1463-1477.

Depicted below are the analytic solution along with solutions illustrating models with consistent  and inconsistent numerics.  The COAMPS solutions show that even on a very coarse grid (relative to the terrain), the correct solution can still be captured and problems with metric inconsistencies are still obvious. 

9 January 2004, W. Skamarock
7 October 2005, Updated, W. Skamarock
9 December  2005, Updated, W. Skamarock

 

The following plots depict the vertical velocity w = dz/dt. See the Schaer et al (2002) and Klemp et al (2003) paper for plots of the full fields. 




solution from model with inconsistent and consistent numerics


COAMPS solution on 1000 m horizontal grid with inconsistent and consistent numerics