SRNWP workshop - Bologne

Short range ensemble forecasting at Météo-Francestatus and plans

J. Nicolau, Météo-France

SRNWP workshop - Bologne

Outline• Operational configuration• Post-processing• LAMEPS experiment• Combination of different SVs sets (Hungary)• Forecasting Extreme Water Levels in Estuaries• Forecasting uncertainty on wind power• Future plans

SRNWP workshop - Bologne

• Ensemble based on Météo-France operational global model ARPEGE (variable mesh) PEACE (Prévision d’Ensemble A Courte Échéance)

• T358c2.4 version (operational ARPEGE resolution ~20km over France)

• Initial state uncertainties with SVs • 11 members (ARPEGE operational + 10 perturbed

members)• 1 run/day (18H)• Up to 60h

Operational configuration

SRNWP workshop - Bologne

Singular Vectors computation

• Targeting over Atlantic Ocean and Western Europe

• Optimization time window : 0-12h• Total Energy norm (initial and final time)• Selection of the 16 first SVs• Linear combination according to the statistical

errors of analysis• No physics (except diffusion)• Low resolution : TL95 regular truncation

SRNWP workshop - Bologne

Svs targetting area

SRNWP workshop - Bologne

SRNWP workshop - Bologne

SRNWP workshop - Bologne

SRNWP workshop - Bologne

Post-processing : statistical adaptation

• Multi-linear regression (Pseudo-PP)• 2m Temperature, 10m Wind speed• Training (3 years) on the control run • Coefficients computed over the first 24h forecast• Then applied to the corresponding steps (ie coeffs

6h applied at 30h and 54h) + more spread - less unbiaised• ~500 sites over France

SRNWP workshop - Bologne

Calibration• Talagrand diagrams• Dynamical (last 40 days) and global (over all of the sites)

training– + sample size– - no local effects

• ~500 sites over France• 2m temperatures, 10m Wind speed, 24hTP

SRNWP workshop - Bologne

• PEACE coupled with ALADIN• 48H forecasts• 10km mesh grid• 20 cases of heavy precipitations• Compared to observations data (~1100 rain

gauges)

LAMEPS experiment (1)

SRNWP workshop - Bologne

HRHR

LAMEPS experiment (2)

SRNWP workshop - Bologne

Observations

Probabilities from PEACE/ALADIN

Probabilities from PEACE

Probabilities for 12hRR >5,10 and 20mm - Step 24h

24 Sept. 1999

LAMEPS experiment (3)

SRNWP workshop - Bologne

Combination of SVs– Collaboration MF/HMS (E.Hägel) – Experiments on different targetting areas– Computation of a set of SVs on Central Europe – Selection of independent SVs from the first set

and combination– Then integration with the global ARPEGE

based ensemble system for a ten day period

SRNWP workshop - Bologne

MSLP

T850 z500

WS10

Average standard deviation over Hungary for the period 10/07/2004-19/07/2004 for MSLP, ws10, T850, z500 for different experiments with the model ARPEGE

results with combination of SVs

results with the former PEACE target domain

SRNWP workshop - Bologne

Combination of SVs

• The improvement we achieved is comperable with the case when we changed only the target domain

• It would also be possible to use different target times for computing the two sets of SVs, maybe further improvement could be achieved

• Possibility to implement this new computation in the operational PEACE configuration.

• See Edit’s poster for further informations !

SRNWP workshop - Bologne

Uncertainty on wind power

• Project with :– EDF (wind power production data)– EMP (wind power production model)– MF (wind forecast distributions from PEACE)

• Evaluation over 18 months• Selection of wind power sites over France

SRNWP workshop - Bologne

SRNWP workshop - Bologne

Over levelObserved level

Astronomic tide

Under level

Nuclear power plant cooling

Forecasting Extreme Water Levels (1)

Storm surges

SRNWP workshop - Bologne

Storm Surges ModelInitial State

Bathymetry

Storm surges

Atmospheric Forcing (WS, WD, MSLP)

Forecasting Extreme Water Levels (2)

SRNWP workshop - Bologne

Wind speed

MSLP

Wind direction

Forecasting Extreme Water Levels (3)

SRNWP workshop - Bologne

Future plans

• Work on SVs (stretched, physics, area, time, combination)

• Model perturbation• Evolved perturbation• Downscaling

– Coupling with the limited area model ALADIN heavy precipitations predictions

• Post-processing

SRNWP workshop - Bologne

• Great scale forecast : – deterministic model – multi-model approach – different lagged forecast– Ensemble : stamps, spread– Multi-analysis ensemble (initial state sensitivity)

• Sensitive weather– Probabilistic forecat– Multi-ensemble approach

SRNWP workshop - Bologne

Discussion• How to deal with different

models/ensembles ?• How to rely uncertainty from ensembles to

the deterministic forecast from high resolution models (eg epsgrams vs det. Atmograms) ?

• How to rely different distributions (eg « mixed epsgrams ») ?