demeter taiwan, 25-27 october 2003 development of a european multi-model ensemble system for...

DEMETER Taiwan, 25-27 October 2003

Development of a

European Multi-Model Ensemble Systemfor

Seasonal to Interannual Prediction

DEMETER

Noel Keenlyside, Institute für Meereskunde, University of Kiel

Tim Palmer, Renate Hagedorn, and Francisco Doblas-Reyes

European Centre for Medium-Range Weather Forecasts (ECMWF)


Predictability

is a nonlinear system

Since is a nonlinear function of

( )

dXF X

dtd X dF

X J Xdt dXF X

J J X


Perturbed parameters

Stochastic physics

Nonlinear dynamical systems for subgrid-motions (e.g. 2D cloud-resolving models, cellular automata)

Singular vectors

Multi-model ensembles

Possible approaches to representation of model error


Multi-model ensemble system

Partner Atmosphere Ocean

ECMWF IFS HOPE

LODYC IFS OPA 8.3

CNRM ARPEGE OPA 8.1

CERFACS ARPEGE OPA 8.3

INGV ECHAM-4 OPA 8.2

MPI ECHAM-5 MPI-OM1

UKMO HadCM3 HadCM3

• DEMETER system: 7 coupled global circulation models

• Hindcast production for: 1987-1999 (1958-2001)

9 member ensembles

ERA-40 initial conditions

SST and wind perturbations

4 start dates per year

6 months hindcasts


Conceptual background (deterministic view)

SST, Tropics, 1987

verification

SST, Tropics, 1988

MSLP, Tropics, 1988


ACC: SST Tropics


Conceptual background (probabilistic view)

SST, Tropics, 1987

MSLP, Tropics, 1988


Reliability: 2m-Temp.>0

0.0490.9020.147

0.0580.9040.151

0.0990.9230.176

-0.007 0.886 0.107

-0.055 0.838 0.107

0.0680.9030.164

0.222 0.994 0.227

0.0750.9210.153



single-model (54 members)

multi-model

0.222 0.994 0.227

0.170 0.959 0.211



-0.099 0.859 0.041

-0.126 0.850 0.024

-0.016 0.925 0.059

-0.149 0.816 0.035

-0.099 0.861 0.040

-0.075 0.891 0.034

0.061 0.983 0.078

-0.094 0.882 0.024


Impact of ensemble size


Impact of number of models (members)

Multi-model realizationsSingle-model realizations


SOI-Index: 1 month lead (DJF)

Multi-Model

CERFACS

CNRM ECMWF INGV LODYC MPI UKMO

Correlation

0.94 0.93 0.93 0.84 0.92 0.95 0.86 0.94

RPSS 0.70 0.67 0.62 0.44 0.63 0.74 0.38 0.74


NAO-Index: 1 month lead (DJF)

Multi-Model

CERFACS

CNRMECMW

FINGV LODYC MPI UKMO

Correlation

0.68 0.48 0.44 0.43 0.37 0.49 0.23 0.31

RPSS 0.24 0.15 0.17 0.21 0.07 0.19 0.08 0.09


Tropical Cyclone FrequencyLinear correlation of the tropical cyclone

frequency

By F. Vitart ([email protected])

1st May1st August

1st November


Verification

• Bias

• Indices

• Deterministic Scores

• Probabilistic Scores

• Single vs. multi-model

http://www.ecmwf.int/research/demeter/verification

• 54-single vs. multi-model

• Ocean diagnostics


Verification

Start date

Lead timeParameter

Model


http://data.ecmwf.int/data

Retrieve NetCDF

Period # Years

ECMWF 1958 - 2001

44

CNRM 1958 – 2001

44

UKMO 1959 – 2001

43

MPI 1969 – 2001

33

INGV 1973 – 2001

29

LODYC 1974 – 2001

28

CERFACS 1980 – 2001

22


End-user modelling

• DEMETER ensemble hindcasts input for health application (malaria model) agriculture application (crop model)

• Basic idea: explore utility of DEMETER hindcasts give range of uncertainty

• Main problems: sparse data to validate malaria in Africa need of downscaled data


Multi-Model

CERFACS

CNRMECMW

FINGV LODYC MPI UKMO

Correlation

0.50 0.51 0.52 0.34 0.35 0.29 0.03 0.36

RPSS 0.30 0.23 0.23 0.24 0.27 0.26 -0.25 -0.01

Malaria predictions (0º,35ºE)ERA-40 Multi-Model: Terciles Ens-mean


Crop growth monitoring system

Crop Growth Indicator

Jan Feb Aug

Meteo data

Yield

Statistical model

Meteo data ERA / DEMETER data


Wheat yield predictionsusing downscaled DEMETER multi-model

dataFrance Germany

Denmark Greece


Validation of seasonal forecast presented at

European Research FP6-conference, Brussels 2002

Risk of cold / warm winter 2002/03Risk of wet / dry winter 2002/03


Summary• DEMETER multi-model hindcasts data set: 22-44 years available for 7 models (1958 – 2001)

Extensive diagnostics and data publicly available

• Applications: end-to-end systems for seasonal prediction -> actual value

feasibility of skilful predictions: malaria incidence, crop yield

• Multi-model improves over single-model ensembles: main improvement due to reliability

skill also improves because of increase in resolution

• The future: EU-funded ENSEMBLES project (starts April 2004)


Potential Economic Value

Anom > 0.43

Anom > 0


The DEMETER methodology is also being used to study the changing risk of flood

as a result of man's impact on climate

Control Greenhouse

enhanced risk of flooding

Palmer & Räisänen,

Nature (2002)


tourismenergy

Towards the new FP-6 Project ENSEMBLES

agriculture

aid relief

health

• Integrated prediction system for time scales from

seasons to decades and beyond

• Greater diversity of applications

• Incorporation of the whole earth system

• Assessment of reliability of model system used for scenario runs


Tropical Cyclone FrequencyTropical storm number for the tropical Atlantic

(JJASO)

By F. Vitart ([email protected])

Verification

Multi-model


DEMETER MM-Results: NAO-Index (DJF)

7 models: 1987-1999 (13y)

3 models: 1959 - 2001 (43y)

demeter taiwan, 25-27 october 2003 development of a european multi-model ensemble system for...

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