Recent Developments at the

Deutscher Wetterdienst (DWD)

WGNE-meeting

18.-22. Oct. 2010, Tokyo

Michael Baldauf (DWD)

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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 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

Supercomputing environment at DWD (Sept. 2010)

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

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COSMO-EU(LME)

GME COSMO-DE(LMK)

The operational Model Chain of DWD: GME, COSMO-EU and -DE

hydrostaticparameterised convectionx 30 km655362 * 60 GPt = 100 sec., T = 7 days

non-hydrostaticparameterised convectionx = 7 km665 * 657 * 40 GPt = 40 sec., T = 78 h

non-hydrostaticconvection-permittingx = 2.8 km421 * 461 * 50 GPt = 25 sec., T = 21 h(since 16. April 2007)

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 hemispherebut decrease in skill over southern hemisphere

(H. Frank, K. Fröhlich, T. Hanisch, DWD)

31 forecasts from 01.-31.01.2010

ANOC pmsl NH

GME 40km / L40

GME 30km / L60

GME 30 km / L60

GME 40km / L40

GME 30km / L60

BIAS pmsl NH

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

COSMO-EU Parallelsuite COSMO-EU Routine

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)

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

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)

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)

COSMO-EU / RK

COSMO-EU RK (new) COSMO-EU Leapfrog (old)

SYNOP-Verification, 03.02.-06.03.2010, 0 UTC runs

(U. Damrath)

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.

COSMO-EU / RK

checker-board pattern in precipitation

COSMO-EU / RK

Model climatology: monthly average of precipitation 12/2009

observation COSMO-EU Leapfrog COSMO-EU RK

(A. Seifert)

COSMO-EU / RK

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 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)

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. 2010 (20 members)operational: ~2012 (40 members)

Gebhardt et al., 2010, Atmospheric Research, in revision

Generation of Ensemble Members

Variations in Forecast System

for the Representation of Forecast Uncertainty

Initial Conditions Boundaries Model Physics

COSMO-DE-EPS

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

variation of „model physics“

Selection of Configurations

subjective, based on experts, verification

Selection Criteria:

1. large effect on forecasts

2. no „inferior“ configuration

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22

33

55

44

entr_sc

rlam_heat

rlam_heat

q_crit

tur_len

different configurationsof COSMO-DE 2.8 km:

Generation of Ensemble Members

COSMO-DE-EPS

Talagrand Diagram

Oct 7 – Nov 24 200915 days selected(15 ensemble members)

1hr-precipitation24 hrs lead time

grid point verification compared to Radar observations

COSMO-DE-EPS

Probabilistic Verification of Ensemble

Brier Skill Score

reference:deterministic COSMO-DE

Oct 7 – Nov 24 200915 days selected(15 ensemble members)0.4

0.3

0.2

0.1

0.0

threshold in mm/h

1hr-precipitation6-24 hrs lead time

grid point verification compared to Radar observations

COSMO-DE-EPS

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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 2nd order accuracy

Requirements to a next generation global model

G. Zängl, D. Majewski + ICON-Team

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

Temperature at lowest model level on day 14

70 km

70 km, nested nest, 35 km

35 km

Mesh refinement in ICON (G. Zängl, DWD)