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Coupling of EULAG dynamical core with COSMO: Results of idealized numerical experiments

This paper presents the results of idealized numerical experiments on the coupling of the EULAG dynamical core with COSMO. The study tests the technical coupling of the two models using inertia-gravity waves and cold density currents as test cases. The results demonstrate successful coupling and highlight the accuracy and efficiency of the approach.

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Coupling of EULAG dynamical core with COSMO: Results of idealized numerical experiments

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  1. Coupling of EULAG dynamical core with COSMO: results of idealized numerical experiments Bogdan Rosa1, Marcin Kurowski1, Damian Wójcik1, Michał Ziemiański1 and Oliver Fuhrer2 Acknowledgements: Zbigniew Piotrowski1,3 1. Institute of Meteorology and Water Management 2. Meteo Swiss 3. National Center for Atmospheric Research COSMO General Meeting, Rome, 5-9 September 2011

  2. Realization of the CDC plan Task 1.7: Technical testing with COSMO by idealised cases The correct coupling of the EULAG dynamical core into COSMO can be at first tested with the implemented idealised test cases. This testing can be performed ‘by a press of a button’ in COSMO. The staff is now well trained with the idealised tests (see task 1.1), therefore it is not necessary to perform an extended analysis of such idealised tests, but simply to check if any technical coupling problems occur. Performed tests: 1. inertia-gravity wave (Skamarock and Klemp, 1994) 2. cold density current (Straka et al., 1993) COSMO General Meeting, Rome, 5-9 September 2011

  3. Two dimensional time dependent simulation of inertia-gravity waves Skamarock W. C. and Klemp J. B. Efficiency and accuracy of Klemp-Wilhelmson time-splitting technique. Mon. Wea. Rev.122:2623-2630, 1994 Initial potential temperature perturbation Initial potential temperature perturbation outlet inlet km Setup overview: • domain size 300x10km • resolution 1x1km,0.5x0.5km, 0.25x0.25km • rigid free-slip b.c. • periodic lateral boundaries • constant horizontal flow 20m/s at inlet • no subgrid mixing • hydrostatic balance • stable stratificationN=0.01 s-1 • max. temperature perturbation 0.01K • Coriolis force included km Constant ambient flow within channel 300 km and 6000 km long Initial velocity COSMO General Meeting, Rome, 5-9 September 2011

  4. Construction of the computational grid - 1st approach U,V,W,θ C&E U,V,W,θ EULAG W COSMO U,V,T* Level # height Level # height 9.5 km 8.5 km 7.5 km 6.5 km 5.5 km 4.5 km 3.5 km 2.5 km 1.5 km 0.5 km 9.5 km 8.5 km 7.5 km 6.5 km 5.5 km 4.5 km 3.5 km 2.5 km 1.5 km 0.5 km 0 km E 11 10 9 8 7 6 5 4 3 2 1 11 10 9 8 7 6 5 4 3 2 1 10 km 9 km 8 km 7 km 6 km 5 km 4 km 3 km 2 km 1 km 0 km 11 10 9 8 7 6 5 4 3 2 1 10 km 9 km 8 km 7 km 6 km 5 km 4 km 3 km 2 km 1 km 0 km E - extrapolation (U,V, θ) C&E Analytical The problem with asymmetry in potential temperature distribution. COSMO General Meeting, Rome, 5-9 September 2011

  5. Computational grid - 2nd approach U,V,W,θ C&E W U,V,W,θ COSMO EULAG U,V,T* Level # height Level # height 10.0 km E 9.5 km 8.5 km 7.5 km 6.5 km 5.5 km 4.5 km 3.5 km 2.5 km 1.5 km 0.5 km 0 km E 12 11 10 9 8 7 6 5 4 3 2 1 9.5 km 8.5 km 7.5 km 6.5 km 5.5 km 4.5 km 3.5 km 2.5 km 1.5 km 0.5 km 11 10 9 8 7 6 5 4 3 2 1 10 km 9 km 8 km 7 km 6 km 5 km 4 km 3 km 2 km 1 km 0 km 11 10 9 8 7 6 5 4 3 2 1 10 km 9 km 8 km 7 km 6 km 5 km 4 km 3 km 2 km 1 km 0 km E - extrapolation (U,V, θ) C&E Analytical Wave propagates too fast COSMO General Meeting, Rome, 5-9 September 2011

  6. Computational grid – 3rd approach U,V,W,θ C&E W U,V,T* EULAG U,V,W,θ COSMO Level # height Level # height 9.5 km 8.5 km 7.5 km 6.5 km 5.5 km 4.5 km 3.5 km 2.5 km 1.5 km 0.5 km 10 km E 9 km I 8 km I 7 km I 6 km I 5 km I 4 km I 3 km I 2 km I 1 km I 0 km E 11 10 9 8 7 6 5 4 3 2 1 11 10 9 8 7 6 5 4 3 2 1 10 km 9 km 8 km 7 km 6 km 5 km 4 km 3 km 2 km 1 km 0 km 11 10 9 8 7 6 5 4 3 2 1 10 km 9 km 8 km 7 km 6 km 5 km 4 km 3 km 2 km 1 km 0 km E - extrapolation (U,V, θ) I - interpolation (U,V, θ) COSMO General Meeting, Rome, 5-9 September 2011

  7. Results - gravity waves in a short channel Eulag C&E Eulag C&E Eulag C&E COSMO General Meeting, Rome, 5-9 September 2011

  8. Comparison with analytical solution Eulag C&E Analytical COSMO General Meeting, Rome, 5-9 September 2011

  9. Profiles of potential temperature along 5000m height C&E Analytical COSMO General Meeting, Rome, 5-9 September 2011

  10. Gravity waves in a long channel Eulag C&E Eulag C&E Eulag C&E COSMO General Meeting, Rome, 5-9 September 2011

  11. Gravity waves in a long channel C&E Analytical C&E Analytical C&E Analytical COSMO General Meeting, Rome, 5-9 September 2011

  12. Profiles of potential temperature along 5000m height C&E Analytical COSMO General Meeting, Rome, 5-9 September 2011

  13. Two dimensional time dependent simulation of cold blob descending to the ground Straka, J. M., Wilhelmson, Robert B., Wicker, Louis J., Anderson, John R., Droegemeier,Kelvin K., Numerical solutions of a non-linear density current: A benchmark solution and comparisonInternational Journal for Numerical Methods in Fluids, (17), 1993 Experiment configuration: • isentropic atmosphere, θ(z)=const (300K) • periodic lateral boundaries • free-slip bottom b.c. • constant subgrid mixing, K=75m2/s • domain size 51.2km x 6.4km • bubble min. temperature -15K • bubble size 8kmx4km • no initial flow • integration time 15mins open b.c. r periodic b.c. periodic b.c. free-slip b.c. COSMO General Meeting, Rome, 5-9 September 2011

  14. Distribution of potential temperature after 900 sec C&E inviscid 100m C&E viscous – diffusive forcing from COSMO parameterizations 100m COSMO General Meeting, Rome, 5-9 September 2011

  15. Comparison of the potential temperature distribution Cosmo 100m C&E Eulag COSMO General Meeting, Rome, 5-9 September 2011

  16. Comparison of the horizontal velocity distribution Cosmo 100m C&E Eulag COSMO General Meeting, Rome, 5-9 September 2011

  17. Comparison of the vertical velocity distribution Cosmo 100m C&E Eulag COSMO General Meeting, Rome, 5-9 September 2011

  18. Comparison of the potential temperature distribution at resolution 50 m Cosmo 50m C&E Eulag COSMO General Meeting, Rome, 5-9 September 2011

  19. Comparison of the horizontal velocity distribution at resolution 50 m Cosmo 50m C&E Eulag COSMO General Meeting, Rome, 5-9 September 2011

  20. Comparison of the vertical velocity distribution at resolution 50 m Cosmo 50m C&E Eulag COSMO General Meeting, Rome, 5-9 September 2011

  21. Comparison of potential temperature distribution at resolution 25 m Cosmo 25m C&E Eulag COSMO General Meeting, Rome, 5-9 September 2011

  22. Comparison of horizontal velocity distribution at resolution 25 m Cosmo 25m C&E Eulag COSMO General Meeting, Rome, 5-9 September 2011

  23. Comparison of vertical velocity distribution at resolution 25 m Cosmo 25m C&E Eulag COSMO General Meeting, Rome, 5-9 September 2011

  24. CONCLUSIONS 1. MOTIVATION • EULAG code has been successfully implemented in COSMO. • Results of the idealized tests obtained using the hybrid E&C model are in goodqualitative and quantitative agreement both with reference and analytical solutions. • Small differences indicate the need for further testing and verification of the E&C code. • Dynamical core of the developed prototype, cooperates correctly with the diffusive forcing from COSMOparameterizations. COSMO General Meeting, Rome, 5-9 September 2011

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