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Status of the COSMO-1 configuration at MeteoSwiss Guy de Morsier

Status of the COSMO-1 configuration at MeteoSwiss Guy de Morsier. COSMO-GM, Roma, 5.9.2011. Agenda. Motivation Status of the ARPA-SIM collaboration Domain and orography filtering Namelist choices Some results Summary Future. Motivation for COSMO-1. Operational target is for 2015

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Status of the COSMO-1 configuration at MeteoSwiss Guy de Morsier

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  1. Status of the COSMO-1 configuration at MeteoSwiss Guy de Morsier COSMO-GM, Roma, 5.9.2011

  2. Agenda • Motivation • Status of the ARPA-SIM collaboration • Domain and orography filtering • Namelist choices • Some results • Summary • Future

  3. Motivation for COSMO-1 • Operational target is for 2015 • Why increase the grid resolution? - improve representation of forcing (e.g. topography, land use) - better capture non-linear interaction between different scales (e.g. convection) - improve use of observing systemsin the assimilation step • Focus mainly on Alpine region and Alpine specific problems

  4. Target: COSMO-1 suite in 2015 8x dailyCOSMO-1 +24 hours forecasts 1 km grid size, 100 layers 1040 x 700 grid points IFS boundary conditions 10 km grid size, 140 layers4x daily

  5. Status of the ARPA-SIM collaboration • Common domain • Test if a common configuration can be used and a common evaluation of results operated • Nesting strategy compare C-1 in C-7 with C-1 in C-2 • Decrease damping in upper layers cf. Wolfgang Langhans1) • Tune the orographic filtering to the stability of the dynamics • Investigate the sensitivity to the asymptotic turbulent length scale and the vertical level distribution • 1)Convergence of numerical simulations of linear hydrostatic gravity wave, March 11, 2011

  6. Orography filtering (2 extremes) COSMO-1 COSMO-2 COSMO-7 4 Dx Raymond filter + XSO1) 750m Rhine 1) eXtrafilter only for masked highSteps of Orography Rhône V.

  7. Gradient of orography a) NO filter, max.36°, mean 6° b) Std filter, max.25°, mean 4.4° c) 400m xso, max.20°, mean 4.2° d) 300m xso, max.18°, mean 3.8° Compare (CH) to: COSMO-7: max.4°, mean1.1°! COSMO-2: max.15°, mean 2.8° near Mt Blanc a) b) c) d)

  8. Large Alpine Domain 698 x 528 gridpoints 300m filter: max. gr. 18° C-1 with 750m filter: 25° COSMO-2: 15° CPU of COSMO-2 * 4

  9. Orographic spectra C-2 3“

  10. Namelist choices Bold for C-2 operational RED = C-1 Dynamics time step (Dt=10sec, C-2=20) advection (SL, Bott2, l3dstrang, lva_impl_dyn) If possible NO horizontal diffusion divergence damping (xkd=0.1/0.05/0.01) best choice:  upper boundary condition (nrdtau=5/2) *Dt: e-folding time for damping at the model top Physics turbulence (itype_turb=3)

  11. COSMO-1 cases • A. StormCarmen 12 November 2010 • with different orographic smoothing • needs horizontal diffusion (1 slide) • B. Convectivecase 29 May 2010 • with/without horizontal diffusion • different advection codes • C. Stratuscase of 27 October 2009without horizontal diffusion (no slides)

  12. A. Energy spectra CARMEN (12.11.2010) withhor. dif. 24h forecast (u, v, w) from 6 to 10km height Similar results for smaller time steps

  13. B. Convective case with COSMO-1 hd_corr_u_in=0.5 NO horizontal diffusion

  14. Test with a modified advection (U. Blahak) ~ 15 m/s !  Maximum nur noch ~ 3 m/s !

  15. B. Convective case with COSMO-1 Uli Blahak modif. advection NO horizontal diffusion

  16. B. Convective case with COSMO-1 [ m3 ] 001: Uli Blahak modif. advection 002: with horizontal diffusion 003: NO horizontal diffusion

  17. B. Convective case with COSMO-1 Time series of Max. vertical wind Max. horizontal wind Withhorizontaldiffusion NOhorizontaldiffusion (hd) NO hdbut withUB modif.advection

  18. B. Convective case 29 May 2010 24h forecast (u, v, w) from 6 to 10km height

  19. Summary Choice of the orographic filtering is not too bad considering the spectral evaluationbut depends on the model dynamics Stable run can produce meaningless values (horizontal wind) at some particular time Possible to run cases without horizontal diffusion The advection scheme has an impact on the results( more tests needed!)

  20. Future Set up an assimilation cycle for COSMO-1 Regular runs from the assimilation cycle Evaluate against COSMO-2 Need more test cases and/or case studies: - Convection - Stratus - Strong precipitation - Föhn

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