Transcript Development of the very short range forecast, meso

Aktionsprogramm 2003
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
AP 2003: LMK
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Aktionsprogramm 2003
Methods I - LMK-Configuration
• 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)
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Aktionsprogramm 2003
Methods II : LAF-Ensemble (Rapid update cycle)
LMK-forecast runs (18h-forecasts, started every 3h) -> LAF-Ensemble
LMK-data assimilation cycle
• continuous assimilation -> nudging
• short cut-off (<1h)
• use all available data, especially radar reflectivites
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
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Aktionsprogramm 2003
M7: Radar
M8: Latent Heat Nudging
M9: LMK 2.8 km & explicit convection
M10: 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.)
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Aktionsprogramm 2003
Detection of Spokes
Berlin 21.06.2005 22:10 UTC
Original
‘Pos. 3’ of quality product
after spoke detection
Latent Heat Nudging
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Aktionsprogramm 2003
Further development of the concept is needed
Hamburg 30.07.2004 6:15 UTC
after detection of spokes
original
falsely recognized
strongly disconnected spokes
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Aktionsprogramm 2003
'Klops’
reasons:
• total reflection by
convection bubble?
• aerosols?
detection by:
- histograms
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Aktionsprogramm 2003
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?
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Aktionsprogramm 2003
M7: Radar
M8: Latent Heat Nudging
M9: LMK 2.8 km & explicit convection
M10: Verification
M8: Latent Heat Nudging
• Thermodynamic feedback and interactions of LMK
• Improvements of the method
• Alternative methods (?)
 WG + plenary lecture Chr. Schraff
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Aktionsprogramm 2003
M7: Radar
M8: Latent Heat Nudging
M9: LMK 2.8 km & explicit convection
M10: Verification
M9: LMK 2.8 km & explicit convection
• Numerical schemes
• Physical Parameterisations
• Boundary conditions
• case studies
• LMK Testsuite
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Aktionsprogramm 2003
LMK- Numerics
• Grid structure:
• time integrations:
• Advection:
horizontal: Arakawa C
vertical:
Lorenz
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
for u,v,w,p',T:
hor. advection: upwind 3., 4., 5., 6. order
for qv, qc, qi, qr, qs, qg, TKE:
Courant-number-independent (CNI)-advection:
Motivation: no constraint for w (deep convection!)
• Smoothing:
AP 2003: LMK
Euler-schemes:
 WG lecture J. Förstner
CNI with PPM advection
Bott-scheme (2., 4. order)
Semi-Lagrange (trilinear, triquadratic, tricubic)
3D divergence damping
horizontal diffusion 4. order
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Aktionsprogramm 2003
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
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Aktionsprogramm 2003
Test of the dynamical core: linear, hydrostatic mountain wave
Gaussian hill
Half width = 40 km
Height = 10 m
U0 = 10 m/s
isothermal stratification
dx=2 km
dz=100 m
T=30 h
analytic solution:
black lines
simulation:
colours + grey lines
w in mm/s
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Aktionsprogramm 2003
Test of the dynamical core: density current (Straka et al., 1993)
‘ after 900 s. (Reference)
by Straka et al. (1993)
RK3 + upwind 5. order
RK2 + upwind 3. order
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Aktionsprogramm 2003
LMK- physics
• 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
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Aktionsprogramm 2003
Explicitly resolved convection in LMK (case study '26.08.2004')
LM
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Radar
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LMK, Testsuite 1.7
21.09.2005
Aktionsprogramm 2003
Advantages by abandoning the convection parameterisation
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Aktionsprogramm 2003
Example: 18.07.2004, 00 UTC + 10 h
LM
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Radar
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Example: 18.07.2004, 00 UTC + 12 h
LM
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Radar
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LMK
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Aktionsprogramm 2003
Example: 18.07.2004, 00 UTC + 18 h
LM
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Radar
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LMK
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Aktionsprogramm 2003
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
AP 2003: LMK
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21.09.2005
Aktionsprogramm 2003
M7: Radar
M8: Latent Heat Nudging
M9: LMK 2.8 km & explicit convection
M10: Verification
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
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Aktionsprogramm 2003
> 0.1 mm/h
> 2 mm/h
LM, 7km, diagn. prec.
LM, 2.8 km, diagn. prec. (TS 1.1)
LMK, progn. prec. (1.3, 1.4)
> 10 mm/h
AP 2003: LMK
LM and LMK
TSS for precipitation events
> 0.1 mm/h, > 2 mm/h, > 10 mm/h
January 2004, 00-h-runs
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Aktionsprogramm 2003
> 0.1 mm/h
> 2 mm/h
LM, 7km, diagn. prec.
LMK, 6-Klassen-Wolkenphysik (1.7)
LMK, 5-Klassen-Wolkenphysik (1.6)
LMK, mit Datenassim. (2.1)
> 10 mm/h
AP 2003: LMK
LM and LMK
TSS for precipitation events
> 0.1 mm/h, > 2 mm/h, > 10 mm/h
September 2004, 00-h-runs
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21.09.2005
Aktionsprogramm 2003
TSS for precipitation, Exp. 5193 with LHN,
‘07.07.2004 - 19.07.2004’
00 h runs
12 h runs
 LMK,  LM
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Aktionsprogramm 2003
Project LMK: Milestones
• Summer 2003
Start 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.
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Aktionsprogramm 2003
Ende
AP 2003: LMK
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Aktionsprogramm 2003
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, ...)
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21.09.2005
Aktionsprogramm 2003
Small clusters
reasons:
- echoes from
moving obstacles
(ships, wind power
plants)
detection by:
- neighbour pixels
- vertical extension
of signals
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Aktionsprogramm 2003
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)
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Aktionsprogramm 2003
Planung M9:
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 Nudging
ab '1.4.2005'
Start: wenn TS 2.3 am '1.4.05' angelangt ist
Anfangsdaten von TS 2.3
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Aktionsprogramm 2003
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
AP 2003: LMK
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21.09.2005
Aktionsprogramm 2003
LMK - Subprojekte (‚Maßnahmen‘)
M7: Radar
• 5-min DX-Radar-komposits, qualitätskontrolliert
• Europäisches DX Komposit
• (Assimilation von Radarwinden)
M8: Latent Heat Nudging
• Thermodynamische Rückkopplung und Wechselwirkungen des LHN
• Verbesserungen der Methode
• Alternative Methoden (?)
M9: LMK 2.8 km & explizite Konvektion
• Numerische Schemata
• Physikalische Parametrisierung
• Seitliche und obere Randbedingungen
• Fallstudien und Vergleiche
• LMK Testsuite
M10: Verifikation
• Traditionelle Verifikation (Syn/Temp)
• Verifikation anhand von synthetischen Satelliten- and synthetischen Radardaten
• Entwicklung neuer Methoden (Mustererkennung, upscaling, ...)
AP 2003: LMK
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Aktionsprogramm 2003
Further planned tests:
• Idealized test cases especially for the dynamical core
• Linear mountain flow
• isotherm, hydrostatic 
see also 5. SRNWP - Workshop
2003, Bad Orb
• 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 
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21.09.2005
Aktionsprogramm 2003
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
AP 2003: LMK
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21.09.2005
Aktionsprogramm 2003
LMK - Dynamics
• Model equations:
• Base state:
• Prognostic variables:
• Coordinate systems:
non-hydrostatic, full compressible, advection form
hydrostatic
cartesian wind components u, v, w
pressure perturbation p‘, Temperature T (or T‘=T-T0)
humidity var. qv, qc, qi, qr, qs, qg ('prognostic precip.')
TKE
rotated geographical coordinates
generalized terrain-following height coordinate
user-defined vertical stretching
Open questions:
• shallow / deep atmospheric equations
i.e. are terms ~w in advection earth curvature and Coriolis force important?
(diploma thesis)
AP 2003: LMK
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21.09.2005
Aktionsprogramm 2003
Tiefe/flache Atmosphäre
LM-Gleichungen für tiefe Atmosphäre in Kugelkoordinaten:
flache Atmosphäre:
• r~a
• vernachlässige Terme in Advektion und Corioliskraft
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Aktionsprogramm 2003
Metric terms of 3D-turbulence
scalar flux divergence:
terrain following coordinates
analogous:
‚vectorial‘ diffusion of u, v, w
earth curvature
(Baldauf (2005), COSMO-Newsl.)
Idealized test:
3D isotropic diffusion
over sinusoidal orography
without metric terms
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with metric terms
21.09.2005
Aktionsprogramm 2003
Example of explicitly resolved convection in LMK (case '26.08.2004')
LM
AP 2003: LMK
Radar
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LMK, Testsuite 1.7
21.09.2005
Aktionsprogramm 2003
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
AP 2003: LMK
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21.09.2005
Aktionsprogramm 2003
Deep moist convection
2.8 km
Schematic model from
a Colorado storm case
study (Raymer
Hailstorm)
from: R. A. Houze, Jr.: Cloud Dynamics
International Geophysics Series Vol. 53
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Aktionsprogramm 2003
Need for a shallow convection parameterization:
Testsuite 1-5
without shallow convection
pressure jump problem
AP 2003: LMK
operational LM
the ‚truth‘ (?)
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Testsuite 1-6
with simple shallow
convection param.
21.09.2005
Aktionsprogramm 2003
Shallow convection
N-S-crosssection
based on Tiedtke-scheme
rh(with shallow convection)
Diff.: rh(with sh. conv) - rh(without sh. conv.)
Dr. F. Theunert (AGeoBW)
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Aktionsprogramm 2003
Lindenberg Wolken-Radar, 20.05.2005
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Aktionsprogramm 2003
Lindenberg Wolken-Radar, 20.05.2005
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Aktionsprogramm 2003
Lindenberg Wolken-Radar, 20.05.2005
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Aktionsprogramm 2003
Lindenberg Wolken-Radar, 20.05.2005
AP 2003: LMK
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21.09.2005
Aktionsprogramm 2003
Lindenberg Wolken-Radar, 20.05.2005
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