grid length: dx = 2.8 km direct simulation of the coarser parts of deep convection (!?)

21.09.2005

Aktionsprogramm 2003

AP 2003: LMK - 1 -

LMK (LM Kürzestfrist) - Development of a very short range forecast model

COSMO General Meeting, Zürich

21.09.2005

M. Baldauf, A. Seifert, J. Förstner, T. Reinhardt, C.-J. Lenz, P. Prohl, K. Stephan, S. Klink, C. Schraff

21.09.2005


AP 2003: LMK - 2 -

• grid length: dx = 2.8 km • direct simulation of the coarser parts of

deep convection (!?)

• interactions with fine scale topography

• about 50 vertical layers, lowest layer in 22 m (new: 10 m) above ground

• center of the domain 10° E, 50° N

• 421 x 461 grid points

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

Methods I - LMK-Configuration

21.09.2005


AP 2003: LMK - 3 -

LMK-forecast runs (18h-forecasts, started every 3h) -> LAF-Ensemble

Methods II : LAF-Ensemble (Rapid update cycle)

possible alterations in this procedure by:• additional soil moisture analysis (SMA)• split in a ‘forecast run analysis’ and a pure data assimilation cycle• GME, LME and LMK cannot be run at the same time on the computer• bigger time window needed for maintenance of the computer

LMK-data assimilation cycle • continuous assimilation -> nudging• short cut-off (<1h)• use all available data, especially radar reflectivites

21.09.2005


AP 2003: LMK - 4 -

M7: RadarM8: Latent Heat NudgingM9: LMK 2.8 km & explicit convectionM10: Verification

M7: Radar•5-min. DX-Radar-composits (from 16 German Radars)•Detection (Correction) of disturbing echoes --> Quality control flags = Quality product •European DX composit (15 min.)

21.09.2005


AP 2003: LMK - 5 -

Detection of Spokes

Berlin 21.06.2005 22:10 UTC

after spoke detection‘Pos. 3’ of quality productOriginal

Latent Heat Nudging

21.09.2005


AP 2003: LMK - 6 -

Further development of the concept is needed

Hamburg 30.07.2004 6:15 UTC

original after detection of spokes

strongly disconnected spokes

falsely recognized

21.09.2005


AP 2003: LMK - 7 -

'Klops’

reasons:• total reflection by

convection bubble?• aerosols?

detection by:- histograms

21.09.2005


AP 2003: LMK - 8 -

Currently in progress:• Detection of other artificial structures:

• anomalous propagation• arched formed echoes (from other radars)• physical reason for ‚Klops‘ occurrence?

• --> ‚quality product‘

Open tasks:• European radar composit (based on DX data)

‚COSMO radar composit‘ ?European/‘COSMO‘ quality product?

21.09.2005


AP 2003: LMK - 9 -


M8: Latent Heat Nudging•Thermodynamic feedback and interactions of LMK•Improvements of the method•Alternative methods (?)

WG + plenary lecture Chr. Schraff

21.09.2005


AP 2003: LMK - 10 -


M9: LMK 2.8 km & explicit convection•Numerical schemes•Physical Parameterisations•Boundary conditions •case studies•LMK Testsuite

21.09.2005


AP 2003: LMK - 11 -

LMK- Numerics

• Grid structure: horizontal: Arakawa Cvertical: Lorenz

• time integrations: time-splitting between fast and slow modes: 3-timelevels: Leapfrog (+centered diff.) (Klemp, Wilhelmson, 1978)2-timelevels: Runge-Kutta: 2. order, 3. order, 3. order TVD

• Advection: for u,v,w,p',T: hor. advection: upwind 3., 4., 5., 6. order

for qv, q

c, q

i, qr, qs, qg, TKE:

Courant-number-independent (CNI)-advection:Motivation: no constraint for w (deep convection!)Euler-schemes: WG lecture J. Förstner

CNI with PPM advectionBott-scheme (2., 4. order)

Semi-Lagrange (trilinear, triquadratic, tricubic)• Smoothing: 3D divergence damping

horizontal diffusion 4. order

21.09.2005


AP 2003: LMK - 12 -

Questions currently considered:• advection of moisture variables:

– advection or conservation form of equations?

– treatment of the density: diagnostic or extra transport equation?

– Eulerian or Semi-Lagrange approach?

• Properties of time-splitting (Runge-Kutta) schemes:

– stability WG lecture M. Baldauf --> plenary lecture J. Steppeler

– convergence, accuracy

– conservation

• Coupling with physics?underestimation of precipitation in convective events because of too weak coupling?

• Problems with steep orography over the Alps?Cold pools in narrow, deep valleys

21.09.2005


AP 2003: LMK - 13 -

Test of the dynamical core: linear, hydrostatic mountain wave

Gaussian hillHalf width = 40 kmHeight = 10 mU0 = 10 m/sisothermal stratification

dx=2 kmdz=100 mT=30 h

analytic solution: black lines

simulation: colours + grey lines

w in mm/s

21.09.2005


AP 2003: LMK - 14 -

Test of the dynamical core: density current (Straka et al., 1993)

RK2 + upwind 3. order

RK3 + upwind 5. order

‘ after 900 s. (Reference)by Straka et al. (1993)

21.09.2005


AP 2003: LMK - 15 -

• turbulence: 1D, 1-equation model (prognostic TKE) 3D, complete coordinate transformations WG lecture M. Baldauf

1-equation model'moist turbulence' (buoyancy production of TKE

altered by condensation processes)• cloud microphysics: 6-class-scheme (qv, qc, qi, qr, qs, new: graupel qg)

WG + plenary lecture T. Reinhardt 6-class/2-moments-scheme (for research/benchmark purposes)

• radiation: 2-flux-scheme (Ritter, Geleyn, 1992)15 min. update frequency, horizontally averaged

WG lecture T. Reinhardt• soil-vegetation-model 2 levels --> 7 levels• convection: - no cumulus convection parametrization

- ‚simple‘ shallow convection: WG lecture A. Seifert apply only shallow convection part from Tiedtke (1989)

only for cloud 'heights' < 250 hPa

LMK- physics

21.09.2005


AP 2003: LMK - 16 -

Explicitly resolved convection in LMK (case study '26.08.2004')

LMK, Testsuite 1.7RadarLM

21.09.2005


AP 2003: LMK - 17 -

Advantages by abandoning the convection parameterisation

21.09.2005


AP 2003: LMK - 18 -

Example: 18.07.2004, 00 UTC + 10 h

LM LMKRadar

21.09.2005


AP 2003: LMK - 19 -

Example: 18.07.2004, 00 UTC + 12 h

LM LMKRadar

21.09.2005


AP 2003: LMK - 20 -

Example: 18.07.2004, 00 UTC + 18 h

LM LMKRadar

21.09.2005


AP 2003: LMK - 21 -

Currently under consideration in physical processes:

• shallow convection:• initiation?

• cloud microphysics:• tuning of parameters?

• turbulence: • is 3D turbulence significant for the 2.8 km scale?

horizontal diffusion coefficient?• little experience about moisture turbulence

More general tasks:

• behaviour of LMK for the interaction with fine scale orography:Föhn storms, severe downslope winds, ...(compare ALADIN/HIRLAM: several ‚Bora‘ studies)

• general underestimation of precipitation in convective situations

21.09.2005


AP 2003: LMK - 22 -


M10: Verification•Traditional verification (synoptic / upper air)•Verification by synthetic satellite and synthetic radar data•Development of new methods (pattern recognition, upscaling, ...)

WG lecture C.-J. Lenz

21.09.2005


AP 2003: LMK - 23 -

LM and LMK

TSS for precipitation events

> 0.1 mm/h, > 2 mm/h, > 10 mm/h

January 2004, 00-h-runs

LM, 7km, diagn. prec.LM, 2.8 km, diagn. prec. (TS 1.1)LMK, progn. prec. (1.3, 1.4)

> 10 mm/h

> 2 mm/h> 0.1 mm/h

21.09.2005


AP 2003: LMK - 24 -

LM and LMK

TSS for precipitation events

> 0.1 mm/h, > 2 mm/h, > 10 mm/h

September 2004, 00-h-runs

LM, 7km, diagn. prec.LMK, 6-Klassen-Wolkenphysik (1.7)LMK, 5-Klassen-Wolkenphysik (1.6)LMK, mit Datenassim. (2.1)

> 0.1 mm/h

> 10 mm/h

> 2 mm/h

21.09.2005


AP 2003: LMK - 25 -

TSS for precipitation, Exp. 5193 with LHN,‘07.07.2004 - 19.07.2004’

00 h runs

12 h runs

LMK, LM

21.09.2005


AP 2003: LMK - 26 -

Project LMK: Milestones

• Summer 2003Start of the project LMK

• End 2003: First test-suite with LM at high resolution is running.

• End 2004:Prototype version of the LMK-System with data assimilation but without LHN running.

• Autumn 2005:Prototype version of the LMK-System with LHN is running.LMK in quasi-operational mode.

• Early 2006:Start of a pre-operational test-phase.Fine-Tuning and final evaluation of all components of the system.

• End 2006:Start of the operational application.

21.09.2005


AP 2003: LMK - 27 -

Ende

21.09.2005


AP 2003: LMK - 28 -

LMK - (LM-Kürzestfrist)‘Aktionsprogramm 2003’ of 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, ...)

21.09.2005


AP 2003: LMK - 29 -

Small clusters

reasons:- echoes from moving obstacles (ships, wind power plants)

detection by:- neighbour pixels- vertical extension of signals

21.09.2005


AP 2003: LMK - 30 -

Neu zugängliche Testsuiten-Ergebnisse

TS 2.1: mit Datenassimilation• Hauptlaufanalysen (Sept-Nov. 2004)

TS 2.2: mit Datenassimilation–‘Aerosolbug’ behoben

–Druckproblem behoben

–Semi-Lagrange-Transport für Feuchtevariablen

• Hauptlaufanalysen• Vorhersagen (z.Z. Juli + Aug. 2004)

21.09.2005


AP 2003: LMK - 31 -

Geplante LMK-Testsuiten

TS 2.2b: wie TS 2.2, aber mit Bott-2-Advektion in Nichterhaltungsform; ab '1.7.2004'erste TS auf der cos1!

TS 2.3:mit 7-Schichten-Bodenmodell (Verbesserung von Gefrier/Auftauprozessen -> Winterfall) ab '1.2.2005' Rand vom LME, neues Parameterfile,neue Schichteneinteilung (50 Schichten, dz=20 m unten)

TS 3.1:wie TS 2.3 + Latent Heat Nudgingab '1.4.2005'Start: wenn TS 2.3 am '1.4.05' angelangt istAnfangsdaten von TS 2.3

Planung M9:

21.09.2005


AP 2003: LMK - 32 -

Final Remarks and Outlook

• Preliminary test of LM at 2.8km grid-spacing (operational set-up,convection switched off) from Dec 2003 - Feb 2004- stable and robust- deficiencies from explicit convection -> shallow convection needed- sometimes convective structures verify subjectively, sometimes not- pressure discontinuity at lateral boundaries is solved now- spin-up of about 1 h (also at lateral boundaries)

• Re-run of the testsuite for the same starting from Jan 2004 using- RK3-TVD time-split integration with 5th order horizontal advection (no horizontal diffusion required)- full budget equations for rain and snow (prognostic precipitation)- SLEVE (smooth level vertical) coordinate

• Upgrade with new physics / dynamics and data assimilation

• Deterministic and probabilistic products

• Many open questions concerning skill and predictability

21.09.2005


AP 2003: LMK - 33 -

M9: LMK 2.8 km & explizite Konvektion•Numerische Schemata•Physikalische Parametrisierung•Seitliche und obere Randbedingungen •Fallstudien und Vergleiche•LMK Testsuite

M8: Latent Heat Nudging•Thermodynamische Rückkopplung und Wechselwirkungen des LHN•Verbesserungen der Methode•Alternative Methoden (?)

M7: Radar•5-min DX-Radar-komposits, qualitätskontrolliert •Europäisches DX Komposit•(Assimilation von Radarwinden)

M10: Verifikation•Traditionelle Verifikation (Syn/Temp)•Verifikation anhand von synthetischen Satelliten- and synthetischen Radardaten•Entwicklung neuer Methoden (Mustererkennung, upscaling, ...)

LMK - Subprojekte (‚Maßnahmen‘)

21.09.2005


AP 2003: LMK - 34 -

Further planned tests:

• Idealized test cases especially for the dynamical core• Linear mountain flow

• isotherm, hydrostatic • non-isotherm !• non-hydrostatic !• ‚Schär‘

• Non-linear mountain flows !• mountain vortex street !• cold bubble (Straka et al., 1993) • warm bubble in shear flow (Weisman, Klemp, 1982)

• test cases especially for cloud physics scheme• IMPROVE-2

see also 5. SRNWP - Workshop 2003, Bad Orb

21.09.2005


AP 2003: LMK - 35 -

Data assimilation: special requirements for LMK

• Assimilation of structures on the meso--scale necessary <-- deep convection

• Observations:--> need for high resolution, rapidly updated data fields --> radar observations ('precipitation scan')

horizontal resolution: r~1 km, ~1°, temporal resolution: t~5 / 15 min (Germany/Europe) )max. range: ~ 120 km

• assimilation method: - fast - relatively easy to implement --> Latent Heat Nudging

21.09.2005


AP 2003: LMK - 36 -

LMK - Dynamics

• Model equations: non-hydrostatic, full compressible, advection form• Base state: hydrostatic• Prognostic variables: cartesian wind components u, v, w

pressure perturbation p‘, Temperature T (or T‘=T-T0)humidity var. q

v, q

c, q

i, qr, qs, qg ('prognostic precip.')

TKE• Coordinate systems: rotated geographical coordinates

generalized terrain-following height coordinateuser-defined vertical stretching

Open questions: • shallow / deep atmospheric equations

i.e. are terms ~w in advection earth curvature and Coriolis force important?(diploma thesis)

21.09.2005


AP 2003: LMK - 37 -

LM-Gleichungen für tiefe Atmosphäre in Kugelkoordinaten:

Tiefe/flache Atmosphäre

flache Atmosphäre: • r ~ a• vernachlässige Terme in Advektion und Corioliskraft

21.09.2005


AP 2003: LMK - 38 -

Metric terms of 3D-turbulence

scalar flux divergence:

analogous:‚vectorial‘ diffusion of u, v, w(Baldauf (2005), COSMO-Newsl.)

earth curvature

terrain following coordinates

Idealized test:3D isotropic diffusion over sinusoidal orography

without metric terms with metric terms

21.09.2005


AP 2003: LMK - 39 -

Example of explicitly resolved convection in LMK (case '26.08.2004')

LM Radar LMK, Testsuite 1.7

21.09.2005


AP 2003: LMK - 40 -

Zusammenfassung der Verifikationsergebnisse:

- Böen: durchweg höhere Qualität der LMK-Prognose gegenüber der

LM-Routine infolge des feineren numerischen Gitters

- Niederschlag: LMK-Ergebnisse liefern teilweise bessere Resultate bei der Verifikation als das LM

- Verschiedene Tests (e.g. Parameterisierung der flachen Konvektion, Datenassimilation) führen zu besseren Verifikationsergebnissen bei einigen Parametern, andere Parameter verifizieren weniger gut

21.09.2005


AP 2003: LMK - 41 -

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

21.09.2005


AP 2003: LMK - 42 -

Testsuite 1-6with simple shallow convection param.

Testsuite 1-5without shallow convectionpressure jump problem

operational LMthe ‚truth‘ (?)

Need for a shallow convection parameterization:

21.09.2005


AP 2003: LMK - 43 -

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)

21.09.2005


AP 2003: LMK - 44 -

Lindenberg Wolken-Radar, 20.05.2005

21.09.2005


AP 2003: LMK - 45 -


21.09.2005


AP 2003: LMK - 46 -


21.09.2005


AP 2003: LMK - 47 -


21.09.2005


AP 2003: LMK - 48 -


grid length: dx = 2.8 km direct simulation of the coarser parts of deep convection (!?)

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