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Recent Developments at the Deutscher Wetterdienst (DWD) WGNE-meeting 18.-22. Oct. 2010, Tokyo

Recent Developments at the Deutscher Wetterdienst (DWD) WGNE-meeting 18.-22. Oct. 2010, Tokyo Michael Baldauf (DWD). Supercomputing environment at DWD (Sept. 2010). One production and one research computer NEC SX-9, both with: 14 nodes with16 processors / node = 224 vector processors

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Recent Developments at the Deutscher Wetterdienst (DWD) WGNE-meeting 18.-22. Oct. 2010, Tokyo

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  1. Recent Developments at the Deutscher Wetterdienst (DWD) WGNE-meeting 18.-22. Oct. 2010, Tokyo Michael Baldauf (DWD)

  2. Supercomputing environment at DWD (Sept. 2010) • One production and one research computer NEC SX-9, both with: • 14 nodes with16 processors / node = 224 vector processors • Peak Vector Performance / CPU: 100 GFlopsPeak Vector Performance / node: 1.6 TFlopsPeak Vector Performance total: 23 TFlops • main memory / node: 512 GBytemain memory total: 7.1 TByte • Internode crossbar switch (NEC IXS): 128 GB/s bidirectional • Login nodes: SUN X4600 • 15 nodes with 8 processors (AMD Opteron QuadCore)/node = 120 processors(2 nodes for interactive login) • main memory / node: 128 GB Database server: two SGI Altix 4700 2

  3. The operational Model Chain of DWD: GME, COSMO-EU and -DE GME COSMO-EU (LME) COSMO-DE (LMK) hydrostatic parameterised convection x  30 km 655362 * 60 GP t = 100 sec., T = 7 days non-hydrostatic parameterised convection x = 7 km 665 * 657 * 40 GP t = 40 sec., T = 78 h non-hydrostatic convection-permitting x = 2.8 km 421 * 461 * 50 GP t = 25 sec., T = 21 h (since 16. April 2007) 3

  4. GME 40 km / L40  GME 30 km / L60 • since 02. Feb. 2010 • reduction of mean grid box size 1384 km²  778 km² • increase of number of vertical levels, increase of resolution in troposphere/tropopause • prognostic rain and snow  additional output fields  boundary values for COSMO-EU Mainly improvement on northern hemisphere but decrease in skill over southern hemisphere (H. Frank, K. Fröhlich, T. Hanisch, DWD)

  5. GME 30 km / L60 31 forecasts from 01.-31.01.2010 ANOC pmsl NH BIAS pmsl NH GME 30km / L60 GME 40km / L40 GME 40km / L40 GME 30km / L60

  6. COSMO-EU with boundary values for QR, QS from GME30L60 COSMO-EU Parallelsuite COSMO-EU Routine

  7. Use of GPS - radio occultation (bending angles) in the 3DVar-Assimilation of GME (since 03. Aug. 2010) • Advantages of GPS radio occultations (bending angles) • high vertical resolution  even vertical thinning of data required! • globally accessible, approximately equally spaced • not influenced by clouds • measurement of the bending angle is almost bias free, temporally stable, independent from the instrument • number of profiles is proportional to the product of the sending GNSS-satellites (GPS, Galileo, GLONASS) and receiving LEOs: • CHAMP, GRACE-A (research satellites) • FORMOSAT-3 / COSMIC ( 6 research satellites) • GRAS (Metop-A) •  ~ 2000/d (May 2010) (H. Anlauf, DWD)

  8. Use of GPS - radio occultation in the 3DVar-Assimilation of GME geopotential in 500 hPa: anomaly correlation of southern hemisphere for July 2010 with GPS without GPS (A. Rhodin)

  9. COSMO-EU (7 km): (since 29. June 2010) Replacement of the dynamical core ('Leapfrog-scheme', Klemp, Wilhelmson (1978) MWR) by the 'Runge-Kutta-scheme' (Wicker, Skamarock (2002) MWR, Baldauf (2010) MWR) Goal: 'convergence' of the dynamical cores of COSMO-EU and COSMO-DE • Motivation: • higher accuracy of the RK-scheme towards leapfrog (in particular better horizontal advection for the dynamic variables);additionally better transport schemes for humidity variables • maintenance: only to foster one dynamical core • future developments are easier to do with a 2-timelevel scheme instead of a 3-timelevel scheme, e.g. physics-dynamics-coupling (G. Zängl, M. Baldauf, A. Seifert, J.-P. Schulz, DWD)

  10. COSMO-EU / RK Measurements to reduce a pressure bias • more accurate discretization of metrical terms (in pressure gradient)for the stretched vertical coordinate (Gal-Chen-coord.)( definition: main levels geometrically are situated in the middle of the half levels) • improved lower (slip-) boundary condition for w: upwind 3rd order + extrapolation of vh to the bottom surface • Introduction of a subgrid scale orography (SSO)-scheme (Lott, Miller (1997) QJRMS) • use of a new reference atmosphere (allows z ) • consistent calculation of base state pressure p0(z) on the main levels (i.e. not by interpolation but by analytic calculation)

  11. COSMO-EU / RK SYNOP-Verification, 03.02.-06.03.2010, 0 UTC runs COSMO-EU RK (new) COSMO-EU Leapfrog (old) (U. Damrath)

  12. COSMO-EU / RK • Measurements to improve the precipitation forecast • 'checkerboard' pattern in precipitationcan be eliminated by an increase in the calling frequency of the convection scheme (nincconv=10  4!)(remark: different time steps: Leapfrog dt=40 sec.; RK dt=66 sec.) • precipitation underestimation during summer was caused by a bug in thephysics-dynamics-coupling: qi-detrainment tendencies of the improved Tiedtke convection scheme were lost.

  13. COSMO-EU / RK checker-board pattern in precipitation

  14. COSMO-EU / RK Model climatology: monthly average of precipitation 12/2009 observation COSMO-EU Leapfrog COSMO-EU RK (A. Seifert)

  15. Main changes in the COSMO-DE • use of the extended radar composit for the Latent Heat Nudging (LHN):16 additional radar stations from Netherlands , Belgium, France, and Switzerland (since 31.03.2010)up to now only crude quality control by clutter filtering and 'gross error detection' (K. Stephan) • vertically implicit TKE diffusion (instead of an explicit scheme; stability) Baldauf, Seifert, Majewski, et al.: "Operational convective-scale numerical weather prediction with the COSMO model", submitted to MWR • current developments: • COSMO PP KENDA: km-scale ensemble data assimilation use LETKF methodsproject leader: Chr. Schraff (DWD) • COSMO PP UTCS: Unified turbulence - shallow convection schemeproject leader: D. Mironov (DWD) • COSMO PP CDC: Conservative dynamical coreproject leader: M. Baldauf (DWD)

  16. Current Status ofCOSMO-DE-EPS Susanne Theis, Christoph Gebhardt, Michael Buchhold, Zied Ben Bouallègue, Roland Ohl, Marcus Paulat, Carlos Peralta with support by: Helmut Frank, Thomas Hanisch, Ulrich Schättler, etc Gebhardt et al., 2010, Atmospheric Research, in revision Start of pre-operational phase: Oct. 2010 (20 members) operational: ~2012 (40 members)

  17. COSMO-DE-EPS Generation of Ensemble Members Variations in Forecast System for the Representation of Forecast Uncertainty Initial Conditions Boundaries Model Physics

  18. COSMO-DE-EPS Generation of Ensemble Members COSMO 7km • Variation of boundary conditions • By COSMO 7km runs driven by different global models • Which computers are used? • at ECMWF: „7 km Ensemble“ • at DWD: COSMO-DE-EPS GME IFS GFS …etc… transfer of data

  19. 1 2 3 4 5 COSMO-DE-EPS Generation of Ensemble Members • variation of „model physics“ Selection of Configurations subjective, based on experts, verification Selection Criteria: 1. large effect on forecasts 2. no „inferior“ configuration different configurations of COSMO-DE 2.8 km: entr_sc rlam_heat rlam_heat q_crit tur_len

  20. COSMO-DE-EPS Talagrand Diagram Oct 7 – Nov 24 2009 15 days selected (15 ensemble members) grid point verification compared to Radar observations 1hr-precipitation 24 hrs lead time

  21. COSMO-DE-EPS Probabilistic Verification of Ensemble Oct 7 – Nov 24 2009 15 days selected (15 ensemble members) Brier Skill Score 0.4 0.3 0.2 0.1 0.0 grid point verification compared to Radar observations reference: deterministic COSMO-DE 1hr-precipitation 6-24 hrs lead time threshold in mm/h

  22. ICON (Icosahedral Nonhydrostatic) Common project DWD - Max-Planck-Inst. f. Meteorology, Hamburg Requirements to a next generation global model • Applicability on a wide range of scales in space and time→„seamless prediction“ • (Static) mesh refinement and limited area model (LAM) option • Scale adaptive physical parameterizations • Conservation of mass (chemistry, convection resolving), energy? • Scalability and efficiency on massively parallel computer systems with more than 10,000 cores • Operators of at least 2nd order accuracy G. Zängl, D. Majewski + ICON-Team 22

  23. Baroclinic wave test with moisture • Modified baroclinic wave case of Jablonowski, Williamson (2008) test suite with moisture and Seifert, Beheng (2001) cloud microphysics parameterization (one-moment version; QC, QI, QR, QS) • Initial moisture field: RH=70% below 700 hPa, 60% between 500 and 700 hPa, 25% above 500 hPa; QV max. 17.5 g/kg to limit convective instability in tropics • Transport schemes for moisture variables: Horizontal: Miura (2007) 2nd order with flux limiter Vertical: 3rd-order PPM with slope limiter • Grid resolutions 70 km and 35 km, 35 vertical levels • Results are shown after 14 days

  24. Mesh refinement in ICON (G. Zängl, DWD) Temperature at lowest model level on day 14 70 km 35 km 70 km, nested nest, 35 km

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