PRUDENCEPRUDENCE

STARDEXSTARDEX

MICEMICE

http://www.cru.uea.ac.uk/projects/mps/

STARDEXSTAtisical and Regional

dynamical Downscaling of EXtremes for European regions

Clare GoodessClimatic Research Unit, UK

http://www.cru.uea.ac.uk/projects/stardex/

The STARDEX team• University of East Anglia, UK • King's College London, UK• Fundación para la Investigación del Clima, Spain • University of Bern, Switzerland • Centre National de la Recherche Scientifique, France• Servizio Meteorologico Regional, ARPA-Emilia Romagna, Italy• Atmospheric dynamics group, University of Bologna, Italy• Danish Meteorological Institute, Denmark • Eidgenössische Technische Hochschule, Switzerland• Fachhochschule Stuttgart - Hochschule für Technik, Germany• Institut für Wasserbau, Germany• University of Thessaloniki, Greece

The STARDEX objectives

• To rigorously & systematically inter-compare & evaluate statistical & dynamical downscaling methods for the reconstruction of observed extremes & the construction of scenarios of extremes for selected European regions.

• To identify the more robust downscaling techniques & to apply them to provide reliable & plausible future scenarios of temperature & precipitation-based extremes for selected European regions.

Statistical downscaling

Relationships between larger-scale climate variables & local surface climate variables, derived from observed data, are applied to climate model output……...

based on the two assumptions that:• larger-scale variables are more reliably simulated• relationships remain valid in a changed climate

Spatially coherent changes in extremes

have occurred over the last 40 years...

1958-2000 trend JJA heat wave duration

Scale is days per year. Red is increasing Malcolm Haylock, UEA

Property damage: US$ 13 bnProperty damage: US$ 13 bnFatalities: 27,000 (14,800 in France)Fatalities: 27,000 (14,800 in France)

Western EuropeWestern EuropeAugust 2003August 2003

1958-2000 trend in JJA heavy rain events

Scale is days per year. Blue is increasing

Central and Eastern EuropeCentral and Eastern EuropeAugust 2002August 2002

Fatalities: > 100Fatalities: > 100Economic losses: > US$18 bnEconomic losses: > US$18 bnInsured losses: > US$3 bnInsured losses: > US$3 bn

Malcolm Haylock, UEA

In part, these changes can be explained by changes in circulation

& other predictors

e.g., Heavy winter rainfall and links with North Atlantic Oscillation/SLPHaylock & Goodess, IJC, 2004

The STARDEX SDS methods • multiple linear regression• canonical correlation analysis• artificial neural networks• multivariate autoregressive model• conditional re-sampling & other analogue-based methods• methods based on a potential precipitation circulation

index & critical circulation patterns• conditional weather generator• local & dynamical scaling

Handling many combinations of different

methods (20+), regions (7), indices (13) & seasons (4)

was difficult!

Key messages from the STARDEX verification work

Skill varies station-station, season-season, index-index, method-method

SE England: Haylock et al., IJC

Winter Spring

Summer Autumn

A2 scenario changes for the W Alps: Schmidli et al., GRL

In majority of cases no consistently superior model, so a major recommendation is to use a range of the better SDS methods – just as the recommendation is to use multiple GCMs/RCMs

Winter

A2 scenario changes for the W Alps: Schmidli et al., GRL

Uncertainties are larger/skill lower – so use scenarios of summer rainfall with care

Winter

Summer

Projected changes in flow duration

Cochem gauge, Mosel (USTUTT-IWS)

Black: presentGreen: B2, 2080sRed: A2, 2080s

% change in greatest 5-day winter rainfallA2, 2080s

% change in greatest 5-day winter rainfall, 1958-2001,611 stations

We have produced recommendations and guidelines for those wanting to undertake SDS – and to help users identify the most suitable methods

For example:

• Robustness criteria

• Applications criteria

• Performance criteria

http://www.cru.uea.ac.uk/projects/stardex

We have produced outputs in a wide range of formats: reports, papers and information sheets

So STARDEX provides a sound scientific starting

point for ENSEMBLES…..

http://www.cru.uea.ac.uk/projects/stardex/