m. baldauf , k. helmert, b. hassler, k. stephan, s. klink,

10./11.04.2006

Aktionsprogramm 2003

AP 2003: LMK - 1 -

LMK (Lokal-Modell-Kürzestfrist)

3rd COPS and GOP WorkshopUniversity of Hohenheim, Stuttgart

10./11.04.2006

M. Baldauf, K. Helmert, B. Hassler, K. Stephan, S. Klink,

C. Schraff, A. Seifert, J. Förstner, T. Reinhardt, P. Prohl,

C.-J. Lenz, U. Damrath Deutscher Wetterdienst, Offenbach, Germany

F. TheunertAmt für Wehrgeophysik, Traben-Trarbach, Germany

10./11.04.2006


AP 2003: LMK - 2 -

Outline

• LMK - Project

• Case study examples of precipitation; verifications

• Developments

• Physical Parameterisations

• Dynamics, Numerics

• Latent Heat Nudging

• Radar quality product

• Time table

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AP 2003: LMK - 3 -

LMK - (Lokal-Modell-Kürzestfrist) Subproject P2 of the ‘Aktionsprogramm 2003’ (DWD)

Goals

• Development of a model-based NWP system for very short range (‘Kürzestfrist’) forecasts (2-18 h) of severe weather events on the meso- scale, especially those related to

– deep moist convection (super- and multi-cell thunderstorms, squall-lines, MCCs, rainbands,...)

– interactions with fine-scale topography(severe downslope winds, Föhn-storms, flash floodings, fog, ...)

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AP 2003: LMK - 4 -

• grid length: x = 2.8 km

• direct simulation of the coarser parts of deep convection

• interactions with fine scale topography

• timestep t=30 sec.

• 421 x 461 x 50 grid points~ 1200 * 1300 * 22 km³lowest layer in 10 m above ground

• forecast duration: 18 h

• center of the domain 10° E, 50° N

• boundary values from LM / LME(x = 7 km)

LMK-Configuration

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AP 2003: LMK - 5 -

LMK 2.8 km & explicit convection (M9)•Numerical schemes•Physical parameterizations•Lateral and upper boundaries•Case studies and intercomparison•LMK Testsuites

Latent Heat Nudging (M8)•Thermodynamic feedback and interactions of LHN•Adaptation of LHN to prognostic precipitation

Radar (M7)•5-min DX-radar composit, European composit •pattern recognition of false echoes --> DXQ - quality product

Verification (M10)•Traditional verifikation (Syn/Temp)•Use of synthetic satellite- and synthetic radar tools•New methods (pattern recognition, upscaling, ...)

LMK - Subprojects (‚Measurements‘)

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AP 2003: LMK - 6 -

Deep Convection none!-> no distinction between convective and stratiform precipitation!

Shallow ConvectionTiedtke (1989) shallow conv., only for Hcloud < 2 km

Physical Parameterisations (I)

Soil-Vegetation-Model

LM LMK

TERRA, 7 levels, additional freezing/melting

Tiedtke (1989)

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AP 2003: LMK - 7 -

Monthly Mean of diurnal cycle of area averaged precipitation, July 2004

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AP 2003: LMK - 8 -

12.07.2004

02.07.2004

07.07.2004

18.07.200417.07.2004

...... radar

___ LMK, 00 UTC

___ LM, 00 UTC

precipitation: diurnal cycle of area average

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AP 2003: LMK - 9 -

Monthly precipitation mean of ‚July 2004‘

ground obs. radar obs. LM

LMK w/o DA LMK + DA LMK + DA

Mean: 103 mm Mean: 80 mm Mean: 95 mm

Mean: 67 mm Mean: 78 mm Mean: 72 mm

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AP 2003: LMK - 10 -

12.07.2004

02.07.2004

07.07.2004

18.07.200417.07.2004

...... radar

___ LMK, 00 UTC

___ LM, 00 UTC


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AP 2003: LMK - 11 -



24h precipitation sum ‚12.07.2004, 06...30 UTC‘

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AP 2003: LMK - 12 -

12.07.2004

02.07.2004

07.07.2004

18.07.200417.07.2004

...... radar

___ LMK, 00 UTC

___ LM, 00 UTC


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AP 2003: LMK - 13 -




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AP 2003: LMK - 14 -

12.07.2004

02.07.2004

07.07.2004

18.07.200417.07.2004

...... radar

___ LMK, 00 UTC

___ LM, 00 UTC


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AP 2003: LMK - 15 -

Example: 18.07.2004, 00 UTC + 10 h

LM LMKRadar

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AP 2003: LMK - 16 -

Example: 18.07.2004, 00 UTC + 12 h

LM LMKRadar

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AP 2003: LMK - 17 -

Example: 18.07.2004, 00 UTC + 18 h

LM LMKRadar

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AP 2003: LMK - 18 -

True skill statistics (TSS)

for precipitation rates

July 2004, 12-UTC-runs

LMK: averaging to the 9 neighbouring grid points

=TS 2.2=TS 2.2b=TS 1.7=TS 1.6=TS 1.5

> 0.1 mm/h > 2 mm/h

> 10 mm/h

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AP 2003: LMK - 19 -

LM and LMK: ETS for gusts > 20 m/s, January 2004, 00-UTC-runs

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AP 2003: LMK - 20 -

Bias (mean error) of 2m-temperature, July 2004, 00-h-runs

=TS 1.5=TS 1.6=TS 1.7=TS 2.2=TS 2.2b

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AP 2003: LMK - 21 -

Conclusions, Verification results:

• Precipitation:

• LMK delivers partly better verification results than LM/LME

• Diurnal cycle (especially time of maximum) is often more realistic

• problem up to now: general underestimation of the precipitation amount in convective events solution proposals: improvement in physics-dynamics-coupling, cloud physics, shallow convection, subscale cloud coverage

• Gusts: better quality of LMK-forecasts compared to LM/LME because of finer numerical (vertical and horizontal) and no convection param.

• 2m-temperature:stronger bias than in LM, because no soil moisture analysis (SMA) is used up to now; can LHN help?

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AP 2003: LMK - 22 -






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AP 2003: LMK - 23 -

Deep Convection

Shallow Convection Tiedtke (1989) shallow conv., only for Hcloud < 2 km

Physical Parameterisations (I)

Soil-Vegetation-Model

LM LMK

TERRA, 7 levels, additional freezing/melting of snow

Tiedtke (1989) none!-> no distinction between convective and stratiform precipitation!

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AP 2003: LMK - 24 -

Shallow convection

based on Tiedtke-schemeN-S-crosssection

rh(with shallow convection) Diff.: rh(with sh. conv) - rh(without sh. conv.)

Dr. F. Theunert (AGeoBW)

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AP 2003: LMK - 25 -

Radiation

Physical Parameterisations (II)

Cloud Microphysics 5-class-scheme 6-class (Graupel)-scheme

6-class/2 moments-scheme(Seifert, Beheng, 2000)

(for research/benchmark purposes)

Turbulence• 1-dim.• 1 eq. model (progn. TKE)

2-flux-scheme (Ritter, Geleyn,1992)

• 3-dim., full coordinate transforms (Herzog et al., 2002; Baldauf, 2005)

• 1 eq. model (progn. TKE) • moist turbulence (=condensation alters

buoyancy-prod. of TKE)

LM LMK

upscaling, higher frequency

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AP 2003: LMK - 26 -

Underestimation of precipitation in LMK

• systematic underestimation of ~20 % in many cases• even enhanced in strong convective situations

Possible solution approaches:• enhancement of subscale coverage in the boundary layer

cloud diagnostic scheme• change of entrainment-/detrainment-coefficients in the

parameterisation of shallow convection• Tuning of cloud physics: reduced evaporation of rain below cloud base

Side effects:• all changes influence cloud coverage and 2m-temperature

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AP 2003: LMK - 27 -

LMK 3.17 + changes in moisture turbulence (enhanced subscale coverage)

+ changes in shallow convection (enhanced entrainment/detrainment)

Sensitivity study for the problem of underestimation of precipitation

case study ‚26.08.2004‘

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AP 2003: LMK - 28 -

Radiation

Physical Parameterisations (II)

Cloud Microphysics 5-class-scheme 6-class (Graupel)-scheme

6-class/2 moments-scheme(Seifert, Beheng, 2000)

(for research/benchmark purposes)

Turbulence• 1-dim.• 1 eq. model (progn. TKE)

2-flux-scheme (Ritter, Geleyn,1992)

• 3-dim., full coordinate transforms (Herzog et al., 2002; Baldauf, 2005, 2006)

• 1 eq. model (progn. TKE) • moist turbulence (=condensation alters

buoyancy-prod. of TKE)

LM LMK

upscaling, higher frequency

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AP 2003: LMK - 29 -

Metric terms of 3D-turbulence

scalar flux divergence:

scalar fluxes:

analogous:‚vectorial‘ diffusion of u, v, w

Baldauf (2005), COSMO-Newsl. Nr. 5

earth curvature

terrain following coordinates

LES-3D-turbulence model from ‘Litfass-LM’ Herzog et al. (2003) COSMO Techn. rep. 4

vertical

horizontal(cartesian)

10./11.04.2006


AP 2003: LMK - 30 -

total precip. in 18 h

Real case study: LMK (2.8 km resolution) ‚12.08.2004, 12 UTC-run‘

‚3D-turb., with metric‘ - ‚1D‘

10./11.04.2006


AP 2003: LMK - 31 -

Advectionu, v, w, T, p‘

Numerics

Grid

horizontal: centered diff. 2. ordervertical: implicit 2. order

Bott-2, conservation form orSemi-Lagrange, tricubic/trilin.

horizontal: upwind 3., 5. ordercentered diff. 4., 6. order

vertical: implicit 2. orderimplicit 3. order

Time integration 3-timelevels: Leapfrog

horizontal: Arakawa-Cvertical: Lorenz

2-timelevels: Runge-Kutta 2. order, 3. order, 3. order TVD

LM LMK

Advectionqv, qc, qi, qr, ..., TKE

qv, qc: centered diff.2. orderqi: Lin, Rood qr, qs: Semi-Lagrange (trilin.)

Smoothing

Divergence damping

4. order diffusion

Asselin-filtering

4. order diffusion (?)

filtering of orographyfiltering of orographystronger filtering of the Alps

10./11.04.2006


AP 2003: LMK - 32 -

Current work in Dynamics:

• diabatic terms in pressure equation

• influence of deep/shallow atmosphere

Current work in Numerics:

• unrealistic cold temperatures in narrow valleys (‚cold pool problem‘)

• is due to pressure gradient in terrain following coordinates --> solution by

• Dynamic lower boundary condition (Gassmann, 2004)

• slope dependent orographic filtering

• modified physics-dynamics-Coupling

• improved 3. order vertical advection for dynamic variables (u,v,w,T,p‘)

• radiative upper boundary condition

10./11.04.2006


AP 2003: LMK - 33 -






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AP 2003: LMK - 34 -

ground obs.:Synop, ship, buoy

upper air obs.:AMDAR,Radiosonde (TEMP)PILOT

Latent Heat Nudging

Data assimilation

T2m Soil moisture

LM LMK

SMA

Nudging

SMA (?)(not used up to now)

Radarprecipitation scanresolution: 1 km * 1°

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AP 2003: LMK - 35 -

Basics of Latent Heat Nudging

Differences (or ratios) between (radar) measured and simulated precipitation rates are interpreted as a lack/surplus of latent heat along the trajectory of a condensed particle.

Basic assumption of LHN: this relation is valid in a vertical model columnvertical structure of latent heating <--> temperature increments (optional: moisture increments, e.g. by conservation of relative humidity)

10./11.04.2006


AP 2003: LMK - 36 -

scores for hourly precipitation : with latent heat nudging / without latent heat nudging

Testsuite ‚Juli 2004‘ (7.-16.7.04)

>2.0 mm>0.1 mm threshold values

FBI

ETS

12-UTC forecasts

10./11.04.2006


AP 2003: LMK - 37 -


Testsuite ‚Juli 2004‘ (7.-16.7.04)

>2.0 mm>0.1 mm threshold values

FBI

ETS

18-UTC forecasts

10./11.04.2006


AP 2003: LMK - 38 -

>2.0 mm

FBI

ETS

>0.1 mm threshold values


Testsuite ‚Juli 2004‘ (7.-16.7.04)

0-UTC forecasts

10./11.04.2006


AP 2003: LMK - 39 -

Conclusions; Latent Heat Nudging:

• An assimilation of spatially and temporally highly resolved data is needed to

trigger convection on the LMK scale

• Latent Heat Nudging of radar reflectivities can be used for this task

• Forecasts especially for 12h-, 18h-runs can be improved.

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AP 2003: LMK - 40 -






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AP 2003: LMK - 41 -

Examples (I)

Negativ spokesHannover, 17.01.2006 16:00 UTC

free pixels or pixel groups

Rostock, 12.02.2006 23:00 UTC

Anomalous propagationBerlin, 6.9.2005 12:55 UTC

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AP 2003: LMK - 42 -

strong positive sectorsreson: technical radar problems

detection is essential !

detection by:- sharp edges- histograms

‚Klops‘

reasons: warm bubbles?

aerosols?

detection by:

- histograms

Examples (II)

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AP 2003: LMK - 43 -

Spoke recognition

Berlin 21.06.2005 22:10 UTC

after spoke recognition‘Pos. 3’ of quality productOriginal

LHN

Examples (III)

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AP 2003: LMK - 44 -

Quality product (DXQ)

same data format as DX-data (planned: BUFR-format)

• Header:

– signature ('DXQ'), date/time, radar location, ....

– coding of radar errors, concerning the whole radar picture:– hardware errors (Wartung, e.g technical problems)– ‘Klops’– radome-Damping

• binary part: pixelwise coding of 8 radar errors (1. bit: recognized, 2. bit: corrected)

1. exceed of threshold in signal processor (RVP) (LOG/SQI/WSP/CCOR/speckle)

2. cluster (def. by 9 neighbouring pixels)

3. spokes - positive- and negativespokes

4. vertical reflectivity profile

5. bright band

6. distance dependent damping

7. ......

8. .......

April 2006: DXQ-composit (QY) and adequate DX-composit (RY) operational

10./11.04.2006


AP 2003: LMK - 45 -

Project LMK: time table of the pre-operational test phase

• July 2003 Start of project LMK• End 2003 First test suites with 2.8 km resolution• End 2004 First test suites with data assimilation

• March 2006: Prototype-version of LMK-system with LHN for ‘summer 2005’ (test suites 3.x).

• April 2006: DXQ-Composit operational• Mai 2006: Start of pre-operational test phase.

Fine-Tuning and evaluation of all components

• June 2006 ‘Introduction group’ (TI14)‘Evaluation group’ (FE 15, WV, AG Evaluierung)

• Dez. 2006: End of AP2003• Spring 2007: Start of operational use after decision of the KG-NWV

and board of directors

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AP 2003: LMK - 46 -

LMK-forecast runs (18h-forecasts, started every 3h) -> LAF-ensembleavailable at: ..., 1, 4, 7, 10, ... , 22, ... UTC

Lagged Average Forecast (LAF)-Ensemble (Prinzip)

LMK-data assimilation cycle (rapid update cycle) • continuous assimilation -> nudging• short cut off ( ~ ½ h)• use all data, especially radar data• adiitionally: split into ‘main run analysis’ and a pure data assimilation cycle

possible changes in this sequence:

• additional soil moisture analysis (SMA)

• GME, LME and LMK cannot run at the same time on the computer

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AP 2003: LMK - 47 -

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AP 2003: LMK - 48 -

from: R. A. Houze, Jr.: Cloud Dynamics International Geophysics Series Vol. 53

Schematic model from a Colorado storm casestudy (Raymer Hailstorm)

Deep moist convection2.8 km

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AP 2003: LMK - 49 -

Explicit Convection in LMK (case study '26.08.2004')

LMK, Testsuite 1.7RadarLM

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AP 2003: LMK - 50 -

Monatsmittel der Niederschläge ‚August 2004‘

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AP 2003: LMK - 51 -

Monthly mean of precipitation (area average over Germany)

Ground Obs. LMK LM

Juli 2004 103 mm 82 mm (TS 2.2) 99 mm

Aug. 2004 88 mm 70 mm (TS 2.2) 84 mm

Sept. 2004 64 mm 55 mm (TS 2.2) 56 mm

Okt. 2004 52 mm 42 mm (TS 2.1) 41 mm

Nov. 2004 72 mm 77 mm (TS 2.1) 68 mm

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AP 2003: LMK - 52 -

Testfall 03.06.2005, 0UTC + 21h

bessere Böenvorhersage im LMK aufgrund höherer horizontaler Auflösung undohne Konvektionsparametrisierung

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AP 2003: LMK - 53 -

Vorteile beim Abschalten der Konvektionsparametrisierung realistischerer Tagesgang des Niederschlags

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AP 2003: LMK - 54 -

Physics (I)• Radiation• Shallow Convection• Coriolis force• Turbulence

DynamicsRunge-Kutta [(phys) + (adv) --> fast_waves ]

‚Physics (I)‘-tendencies n(phys I)

Physics (II)• Cloud Physics

Physics-Dynamics-couplingfields n=(u, v, w, pp, T, ...)n

fields n+1=(u, v, w, pp, T, ...)n+1

fields *=(u, v, w, pp, T, ...)*

‚Physics (II)‘-tendencies n(phys II)

+ n-1(phys II) NEW!

- n-1(phys II) NEW!

Descr. of Advanced Research WRF, v. 2 (2005)

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AP 2003: LMK - 55 -

LMK

Radar

MC2

model intercomparison:MAP IOP 2b(„19./20.09.1999“)heaviest RR during MAP(300mm / 30 h)

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AP 2003: LMK - 56 -

1: MM5

2: WRF

3: MOLOCH

4: Méso-NH

5: LMK

6: Aladin oper. 1999

7: Arpège oper. 1999

8: EZMW oper. 1999

9: EZMW oper. 2002 with MAP-reanalysis

--> LMK performs not bad !:• bias less than for the most other models

• correlation & RMSE better than for operational forecasts, worse than for (tuned?) science models.

LMK

LMKLMK

Bias (mm) RMSE (mm) Correl. coeff.model intercomparison:MAP IOP 2b(„19./20.09.1999“)heaviest RR during MAP(300mm / 30 h)

precipitation scores:

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AP 2003: LMK - 57 -

6-class-cloud-microphysics scheme in LMK

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AP 2003: LMK - 58 -

Testsuite 1-6with simple shallow convection param.

Testsuite 1-5without shallow convectionpressure jump problem

operational LMthe ‚truth‘ (?)

Need for a shallow convection parameterization:

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AP 2003: LMK - 59 -




m. baldauf , k. helmert, b. hassler, k. stephan, s. klink,

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