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
48
Embed
21.09.2005 Aktionsprogramm 2003 AP 2003: LMK - 1 - LMK (LM Kürzestfrist) - Development of a very short range forecast model COSMO General Meeting, Zürich.
Aktionsprogramm 2003 AP 2003: LMK 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
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
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
Aktionsprogramm 2003
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
Aktionsprogramm 2003
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
• 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, qc, qi, 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
Aktionsprogramm 2003
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
Aktionsprogramm 2003
AP 2003: LMK - 13 -
Test of the dynamical core: linear, hydrostatic mountain wave
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
Aktionsprogramm 2003
AP 2003: LMK - 16 -
Explicitly resolved convection in LMK (case study '26.08.2004')
LMK, Testsuite 1.7RadarLM
21.09.2005
Aktionsprogramm 2003
AP 2003: LMK - 17 -
Advantages by abandoning the convection parameterisation
21.09.2005
Aktionsprogramm 2003
AP 2003: LMK - 18 -
Example: 18.07.2004, 00 UTC + 10 h
LM LMKRadar
21.09.2005
Aktionsprogramm 2003
AP 2003: LMK - 19 -
Example: 18.07.2004, 00 UTC + 12 h
LM LMKRadar
21.09.2005
Aktionsprogramm 2003
AP 2003: LMK - 20 -
Example: 18.07.2004, 00 UTC + 18 h
LM LMKRadar
21.09.2005
Aktionsprogramm 2003
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
reasons:- echoes from moving obstacles (ships, wind power plants)
detection by:- neighbour pixels- vertical extension of signals
21.09.2005
Aktionsprogramm 2003
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
Aktionsprogramm 2003
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
Aktionsprogramm 2003
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
Aktionsprogramm 2003
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
Aktionsprogramm 2003
AP 2003: LMK - 34 -
Further planned tests:
• Idealized test cases especially for the dynamical core• Linear mountain flow
• 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
Aktionsprogramm 2003
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
Aktionsprogramm 2003
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. qv, qc, qi, qr, qs, qg ('prognostic precip.')TKE
Open questions: • shallow / deep atmospheric equations
i.e. are terms ~w in advection earth curvature and Coriolis force important?(diploma thesis)
21.09.2005
Aktionsprogramm 2003
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
Aktionsprogramm 2003
AP 2003: LMK - 38 -
Metric terms of 3D-turbulencescalar 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
Aktionsprogramm 2003
AP 2003: LMK - 39 -
Example of explicitly resolved convection in LMK (case '26.08.2004')
LM Radar LMK, Testsuite 1.7
21.09.2005
Aktionsprogramm 2003
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
Aktionsprogramm 2003
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)