limited-area ensembles using targeted svs from ecmwf
DESCRIPTION
Limited-area ensembles using targeted SVs from ECMWF. Inger-Lise Frogner Norwegian Meteorological Institute. Topics. Experiments using targeted SVs for perturbing HIRLAM (QJRMS (2002) 128 , pp 1321-1341) Targeted vs. not targeted perturbations Two case studies Summary/Plans. - PowerPoint PPT PresentationTRANSCRIPT
Limited-area ensembles using targeted SVs from ECMWF
Inger-Lise FrognerNorwegian Meteorological Institute
Meteorologisk institutt met.no
Topics
• Experiments using targeted SVs for perturbing HIRLAM (QJRMS (2002) 128, pp 1321-1341)
• Targeted vs. not targeted perturbations
• Two case studies• Summary/Plans
Meteorologisk institutt met.no
SET-UP LAMTEPS
• LAMTEPS - Limited Area Model Targeted Ensemble Prediction System
• HIRLAM perturbed with targeted EPS from ECMWF (TEPS)
• 48h optimization interval for TSVs.• HIRLAM analyses used• Two different approaches:
– Perturbed ini. and boundary conditions (PB)– Perturbed only initial conditions (NP)
• Test periods in June and Feb. 1997• 28 km, 31 levels, 20+1 ensemble
members
Meteorologisk institutt met.no
I
i
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n
D
didind pe
DNIspread
1 1 1
2)(11
Comparison of TEPS and
operational EPS
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Verified against “superobservations”
THR = 20mm/24hTOTAL PRECIP.
WINTER PERIODVerification time: 40h
TEPSLAMTEPS (PB)
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THR = 30mm/24hTOTAL PRECIP.
WINTER PERIODVerification time: 40h
TEPS
LAMTEPS (PB)
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•
TEPS
LAMTEPS (PB)LAMTEPS (NP)
THR = 2m temp. colder than -6K
compared to climatology.
WINTER
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THR = 2m temp.
colder than -6K
compared to
climatology.
WINTER
TEPSLAMTEPS (PB)LAMTEPS (NP)
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TEPS
LAMTEPS (PB)
LAMTEPS (NP)
THR = 2m temp. warmer than 4K
compared to climatology.
SUMMER
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TEPS
LAMTEPS (PB)
LAMTEPS (NP)
THR = 2m temp. warmer than 4K
compared to climatology.
SUMMER
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Targeted vs. not targeted perturbations
• Motivation: – TEPS perturbations initially small inside the
HIRLAM integration area.– EPS perturbations more uniformly spread
around the hemisphere
• Two different approaches:– Perturbing using TEPS -> LAMTEPS– Perturbing using “operational” EPS -> LAMEPS
• Test period in September 1999 (23 – 30)• Lateral boundary conditions perturbed
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EPS
TEPS
LAMEPS
LAMTEPS
THR = 15mm/24hTOTAL PRECIPITATION
Verification time: 66h
Autumn
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EPS
TEPS
LAMEPS
LAMTEPS
THR = 15mm/24hTOTAL PRECIPITATION
Verification time: 90h
Autumn
Meteorologisk institutt met.no
Two case studies from Sept. 1999 with heavy precipitation
• Case 1: 42 hours forecast from 30 September 1999
• Case 2: 42 hours forecast from 25 September 1999
• “super-observations” representative of the HIRLAM grid constructed (Ghelli and Lalaurette, 2000)
• Kriging method used to obtain estimated area precipitation from point observations
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Case 1: 24h accumulated precipitation, valid at 2 October 1999
AnalysisHIRLAM 50km
(MSLP)