Annual Seminar 2017

ECMWF | Reading | 11-14 September 2017

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Ensemble prediction: past, present and future

Twenty-five years ago, both the ECMWF and the US National Centers for Environmental Prediction (NCEP) started producing global, medium-range ensemble forecasts as part of their operational suites. The implementation of these ensembles induced a paradigm shift in NWP from providing a single forecast, to issuing a range of forecasts that can be used to identify possible future scenarios, to compute the probability of events of interest, and in general to estimate forecast confidence levels. Today, ensembles are routinely used to provide estimates of the probability distributions of analyses and forecasts.

During the Seminar, we discussed whether the existing ensemble designs can continue to deliver improvements, or whether we need to re-consider their configurations. We revisited the main assumptions behind the different strategies used to simulate initial and model uncertainties, and assessed whether there is clear evidence that one approach should be preferred to another. We looked at how global and regional ensembles can complement each other, and whether different ensemble techniques should be used to estimate the initial or forecast state of the atmosphere. Sources and sinks of forecast skill were also discussed.

Seminar aims

The seminar is part of ECMWF's educational programme and is aimed at young scientists but also more established scientists that want to engage more with ensemble prediction.

Presentations and recordings

Monday 11 September

 PresentationRecording
Welcome and opening
Andrew Brown (ECMWF)
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Historical perspective: earlier ensembles and forecasting forecast skill and Global Leading Lyapunov Vectors
Eugenia Kalnay (University of Maryland)
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Historical Review: Foundational studies in atmospheric predictability
Joe Tribbia (NCAR)
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The ECMWF approach to ensemble prediction
Tim Palmer (University of Oxford)
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The virtues of ensemble forecasting
Zoltan Toth (NOAA/ESRL)
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The Canadian approach to ensemble prediction
Peter Houtekamer (CMC)
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Tuesday 12 September

 PresentationRecording
EnKF methods to initialize ensembles
Neill Bowler (UK Met Office)
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Ensemble of data assimilation methods for the initilization of EPS
Laure Raynaud (Météo-France)    
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Combining EDA and SVs to initialize ensemble forecasts
Simon Lang (ECMWF)
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Ensembles in the ocean: an overview
Magdalena Balmaseda (ECMWF)
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Stochastic methods for representing atmospheric model uncertainties in ECMWF's IFS model
Sarah-Jane Lock (ECMWF)
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Ensemble data assimilation using a unified representation of model error
Chiara Piccolo (UK Met Office)
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Ensemble model error at Météo-France
François Bouttier (Météo-France)
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Uncertainty quantification in ocean models
Laure Zanna (University of Oxford)
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Wednesday 13 September

 PresentationRecording
Upscale and downscale error growth
Dale Durran (University of Washington)
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Tropical-extratropical interactions in ensemble predictions from sub-seasonal to decadal scales
Franco Molteni (ECMWF)
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Seasonal forecast ensembles: How confident are predictability estimates of the NAO?
Antje Weisheimer (ECMWF and University of Oxford)
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Ensemble size: how suboptimal is less than infinity?
Martin Leutbecher (ECMWF)
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Ensemble forecast products: supporting users’ decision making
David Richardson (ECMWF)
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Hydrological ensemble prediction
Hannah Cloke (University of Reading)
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Slowly but surely: Observing and supporting the growing use of ensemble products
Renate Hagedorn (DWD)
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Panel discussion: Future directions for ensemble systems video icon

Thursday 14 September

 PresentationRecording
Ensemble verification metrics
Debbie Hudson (BoM)
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Ensemble verification and extreme events
Chris Ferro (University of Exeter)
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Diagnostics of ensemble data assimilation and ensemble forecasts
Mark Rodwell (ECMWF)
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Diagnostic and verification of low-frequency phenomena
Laura Ferranti (ECMWF)
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Ensembles for air quality and atmospheric composition prediction
Angela Benedetti (ECMWF)
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Very high-resolution, non-hydrostatic, short-range ensembles
Inger-Lise Frogner (Norwegian Meteorological Institute)
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The Forecast Skill Horizon
Roberto Buizza (ECMWF)
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Ensembles for climate projections
David Sexton (UK Met Office)
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Organising committee

Roberto Buizza, Martin Leutbecher, Anna Ghelli, Antje Weisheimer, Franco Molteni, Magdalena Alonso-Balmaseda, Sarah-Jane Lock, Tim Stockdale, Massimo Bonavita, David Richardson.