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

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Presentation on theme: "Recent Developments at the Deutscher Wetterdienst (DWD) WGNE-meeting 18.-22. Oct. 2010, Tokyo Michael Baldauf (DWD)"— Presentation transcript:

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

2 2 One production and one research computer NEC SX-9, both with: 14 nodes with16 processors / node = 224 vector processors Peak Vector Performance / CPU: 100 GFlops Peak Vector Performance / node: 1.6 TFlops Peak Vector Performance total: 23 TFlops main memory / node: 512 GByte main memory total: 7.1 TByte Internode crossbar switch (NEC IXS): 128 GB/s bidirectional Supercomputing environment at DWD (Sept. 2010) Login nodes: SUN X 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

3 3 COSMO-EU (LME) GME COSMO-DE (LMK) The operational Model Chain of DWD: GME, COSMO-EU and -DE hydrostatic parameterised convection x 30 km * 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)

4 GME 40 km / L40 GME 30 km / L60 since 02. Feb 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 31 forecasts from ANOC pmsl NH GME 40km / L40 GME 30km / L60 GME 40km / L40 GME 30km / L60 BIAS pmsl NH

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

7 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) Use of GPS - radio occultation (bending angles) in the 3DVar-Assimilation of GME (since 03. Aug. 2010)

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

9 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 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) (G. Zängl, M. Baldauf, A. Seifert, J.-P. Schulz, DWD)

10 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 3 rd order + extrapolation of v h 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 p 0 (z) on the main levels (i.e. not by interpolation but by analytic calculation) COSMO-EU / RK

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

12 Measurements to improve the precipitation forecast 'checkerboard' pattern in precipitation can 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 the physics-dynamics-coupling: q i -detrainment tendencies of the improved Tiedtke convection scheme were lost. COSMO-EU / RK

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

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

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 ) 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 methods project leader: Chr. Schraff (DWD) COSMO PP UTCS: Unified turbulence - shallow convection scheme project leader: D. Mironov (DWD) COSMO PP CDC: Conservative dynamical core project leader: M. Baldauf (DWD)

16 Current Status of COSMO-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 Start of pre-operational phase: Oct (20 members) operational: ~2012 (40 members) Gebhardt et al., 2010, Atmospheric Research, in revision

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

18 Generation of Ensemble Members GFSIFSGME COSMO 7km …etc… transfer of data 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 COSMO-DE-EPS

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

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

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

22 22 ICON (Icosahedral Nonhydrostatic) Common project DWD - Max-Planck-Inst. f. Meteorology, Hamburg 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 2 nd order accuracy Requirements to a next generation global model G. Zängl, D. Majewski + ICON-Team

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


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