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Standardized Test Set for Nonhydrostatic Dynamical Cores of NWP Models

Standardized Test Set for Nonhydrostatic Dynamical Cores of NWP Models. Bill Skamarock (NCAR), Jim Doyle (ONR), Peter Clark, Nigel Wood (MetOffice).

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Standardized Test Set for Nonhydrostatic Dynamical Cores of NWP Models

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  1. Standardized Test Set for Nonhydrostatic Dynamical Cores of NWP Models Bill Skamarock (NCAR), Jim Doyle (ONR), Peter Clark, Nigel Wood (MetOffice) Objective: Compile a set of test cases to verify the correctness and examine the robustness of nonhydrostatic solvers (not full NWP models). Publish this test set (journal article, web page, etc.) to facilitate community use. Today: Propose a test set, invite community input – comments, additions, deletions, etc.

  2. The Need for Test Cases • Test for the correctness of coding, and the appropriateness of approximations (anelasticity, linearizations in the continuous or discrete equations, etc.). • Test robustness, accuracy, and efficiency of the solver. • Documentation: • What solver components are tested by a particular test? • Solution: analytical, numerically converged, subjective? • Setup of tests and interpretation of results • Fine points and issues

  3. Guiding Principles • Tests should be easy to configure (b.c’s, initializations). • Tests should be easy to evaluate (analytical solutions, converged numerical solutions, obvious solution features, simple diagnostics). • Tests should require only minimal physics (dissipation, very simple moist physics). • Tests should testsomething in the solver. • Test set should be a minimal set.

  4. Proposed Test Set Adiabatic flow with no terrain Inertia gravity waves in a periodic channel Density current Adiabatic flow with terrain Resting atmosphere Potential flow over a mountain 2D mountain waves – hydrostatic and nonhydrostatic, linear and nonlinear 3D mountain waves Schaer(MWR 2002; Klemp et al 2003) mountain wave test Moist Convection (squall-lines?, supercells?)

  5. Density Current Test Case (Straka et al, IJNMF, 1993) 2D channel (x , z ; 51.2 x 6.4 km) Initial state: theta = 300 K (neutral) + perturbation (max = 16.2 K) Eddy viscosity = 75 m**2/s (constant)

  6. Density Current Reference Solution (50 meter grid) Potential Temperature (c.i. = 1 K) 4 3 height (km) 2 1 0 0 3 6 9 12 15 18 horizontal distance (km)

  7. Density Current Test Case WRF-mass model, 50 m solution (reference) 100, 200 and 400 m solns. Advection: 5th order (horizontal) 3rd order (vertical) RK3 time integration Timesteps: 1 s (50 m) 1 s (100 m) (stab > 3 s) 2 s (200 m) 4 s (400 m)

  8. Density Current Test Case WRF-mass model, 50 m solution (reference) 100, 200 and 400 m solns. Advection: 2nd order (horizontal) 2nd order (vertical) RK3 time integration Timesteps: 1 s (50 m) 1 s (100 m) (stab > 3 s) 2 s (200 m) 4 s (400 m)

  9. WRF-mass model

  10. Density Current Verification • Density current speed (location at end time). • Minima and maxima for momentum, temperature. • Eddy structure. • Symmetry (for translating solution; U > 0). What Does This Test in a Model? • Coding (time integration, nonlinear terms). • Nonlinear behavior. • Efficiency and robustness • Different timesteps, spatial resolution • Translation

  11. Shaer Test Case (MWR 2002; Klemp et al 2003) Linear Analytic Solution where

  12. Schaer Test Case Leapfrog model dx = 500 m, dz = 300 m 4th order for advection and metric term for omega 4th order advection and 2nd order metric term for omega

  13. Schaer Test Case COAMPS dx = 1000 m, dz = 300 m 4th order advection and metric term for omega 4th order advection and 2nd order metric term for omega

  14. MC2 simulation from MAP case IOP2B (from Benoit et al 2002) MC2 with original Galchen coordinate transformation. MC2 with SL calculation of W and with SLEVE vertical coordinate (Schar et al 2002)

  15. Shaer Test Case (MWR 2002; Klemp et al 2003) Verification: Solution structure and amplitude What Does This Test in a Model Metric terms – pressure gradients, divergence operators and advection (comp of omega) Steady-state solution: not a test of time integration methods (except in SL models). Special Needs? Boundary conditions – wave radiation in horizontal, absorbing layer aloft

  16. Convection: Supercell Tests full nonlinear model. Needs: moist physics (Kessler) Will work with periodic x,y boundaries, constant 2nd order dissipation

  17. Supercell simulation, vertical velocity and rainwater WRF-mass model, time = 1.5 h, z = 1500 m domain – (x,y,z) = (90,90,20) km Uni-directional shear; x,y periodic boundaries

  18. time =1.5 h, z = 1500 m

  19. 2D squall line simulation

  20. Proposed Test Set Adiabatic flow with no terrain Inertia gravity waves in a periodic channel Density current Adiabatic flow with terrain Resting atmosphere Potential flow over a mountain 2D mountain waves – hydrostatic and nonhydrostatic, linear and nonlinear 3D mountain waves Schaer(MWR 2002; Klemp et al 2003) mountain wave test Moist Convection (squall-lines?, supercells?)

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