A Coordinated Regional Downscaling Experiment CORDEX A Coordinated Regional Downscaling Experiment Sponsored by the World Climate Research Programme Colin Jones & Filippo Giorgi Thanks to Grigory Nikulin (SMHI), Daniela Jacob & Paolo Ruti http://wcrp.ipsl.jussieu.fr/SF_RCMTerms.html Generating an ensemble of high-resolution regional climate projections for the majority of land regions of the globe, consistent with a suitable sample of CMIP5 GCM projections.

Higher resolution often results in improved precipitation UKMet: HadCM3

Daily rainfall intensity over the Alps Higher resolution can provide an improved simulation of extremes (HC models)‏ UKMet: HadCM3

Different GCMs can give different regional climate change signals

Winter season temperature change (2016-2045)–(1961-1990) Greater relative differences between simulated climate change signal. Even between 3 members of the same GCM with same emission scenario (ECHAM5 A1B) but different initial conditions.

Circulation plays a 1st order role in determining regional climate variability and still will in the years of anthropogenic climate change

Seasonal Mean temperature averaged over Southern Sweden (500km2) from 3 RCA3 ensemble members all driven by ECHAM A1B scenarios

General Aims and Plans for CORDEX Provide an ensemble of coordinated Regional Climate Scenarios for 1950-2100, for the majority of land-regions of the globe Make this data available and useable to users, with a common diagnostic set and format (following CMIP5) at archives Provide a framework for testing Regional Climate Models and Downscaling techniques for the recent past and future scenarios. Foster coordination between downscaling efforts around the world & encourage local participation in this process esp .developing nations With CMIP5 provide climate simulation data to support IPCC AR5.

More specific aims and plans for CORDEX Develop a matrix of RCD simulations that employ: Multiple GCMs as boundary conditions (BCs) 2. Multiple realizations of a given (single) GCM as BCs 3. Multiple RCMs driven by a given GCM over a given domain 4. Multiple ESD approaches for a given GCM and domain 5. More than 1 representative greenhouse emission scenario 6. With common RCM/ESD domains and resolution 7. With common output variables and frequency 8. In a common format closely following CMIP5 9. Results freely available for subsequent access and use

Sampling the sources of uncertainty in RCD-based Regional climate projections RCD Configuration (Multiple models) AOGCM Configuration (Multiple AOGCMs) Uncertainty in regional climate projection Region Emission/ Concentration Scenarios Internal variability (Multiple realizations) RCD approach (Multiple RCD methods)

What has been decided Selected 6-hourly 3D model level fields as output included in the CMIP5 GCM output protocol. At least 1 RCP4.5 and 1 RCP8.5 member (1950-2100). Also at least 3 ensemble members from decadal prediction (2005-2035) and hindcast runs (1985-2005, 1990-2000). The standard RCM resolution is 50km (many groups plan to also run higher resolutions for selected domains, e.g. ~10km Europe). 50km base resolution to include as many groups as possible 3.Before making GCM forced runs for a given region groups should run the RCM forced by ERA-interim (1989-2008) over that region for model evaluation. 4.An initial (international) focus for future climate scenarios will be Africa with an aim to support the IPCC AR5 process

Decadal hindcasts & predictions CORDEX Phase I experiment design Model Evaluation Framework Climate Projection Framework Multiple regions (Initial focus on Africa) 50km resolution (higher in some regions, Europe: 10km) ERA-Interim BC 1989-2007 RCP4.5, RCP8.5 Multiple AOGCMs Regional Analysis Regional Databanks 1951-2100 Decadal hindcasts & predictions

CORDEX DOMAINS (except Arctic & Antarctica) •12 domains with a resolution of 0.44° (approx. 50x50km²) •Focus on Africa •High resolution ~0.11°x0.11° for Europe (by some institutions)

Evaluation of Annual Mean Precipitation CRU 3.0 REMO Annual mean precipitation [mm/month], 1989-2006 CRU TS3.0 (Mitchell and Jones, 2005)

Evaluation of Annual Mean Temperature Annual mean difference of temperature [K]: REMO-CRU, 1989-2006 Positive bias in areas of upwelling ocean currents

Med-CORDEX (linked to HYMEX) Groups involved in Med-CORDEX ** Includes a coupled Mediterranean - LMD (WRF) ** ICTP-ENEA (RegCM+MIT) ** CNRM (ALADIN) ** MPI (REMO) ** UCLM (PROMES) WRF community … SMHI, COSMOS ARCHIVE: List of the CORE runs (STAND ALONE + COUPLED): 50 km RCM (25 Km) 1989-2008, ERAInterim driven 1950-2100, Scenarios RCP4.5 and/or RCP8.5, AR5-GCM driven

Empirical-Statistical Downscaling in CORDEX CORDEX-ESD group forming: CERFACS, Univ Cape Town, Met.No, Santander, Queensland (so far) Over Africa: Aim to compare ESD and RCM downscaled Climates from common GCM forcings & grids Proposal to make a controlled comparison between various ESD Methods and with RCM downscaling of ERA-interim and CMIP5 Control Climate simulations Use RCMs to investigate the ESD-assumed relationship between large-scales and small(er) scales Initially for: Africa, Europe, and Euro-Mediterranean Need for an active CORDEX-ESD group (?) and more presence of ESD expertise on the WCRP Task Force.

Initial Results from 5 RCMs run for 1989-2008 at 50km forced by ERA-interim boundary conditions RCMs that have/are made the Africa ERA run and will make scenario runs for Africa UCT/UK Met. : PRECIS Santander/Bergen/LMD : WRF U Murcia : MM5 ICTP : RegCM3 UQAM : GEM_LAM Ouranos : CRCM4 CCCma : CanRCM Meteo France : ARPEGE KNMI : RACMO JRC : CLM MPI : REMO DMI : HIRHAM SMHI : RCA CORDEX review article summer 2010

Sampling the sources of uncertainty in RCD-based Regional climate projections RCD Configuration (Multiple models) AOGCM Configuration (Multiple AOGCMs) Uncertainty in regional climate projection Region Emission/ Concentration Scenarios Internal variability (Multiple realizations) RCD approach (Multiple RCD methods)

JAS seasonal mean precipitation 1998-2008

Northern west Africa region Southern west Africa region

Highlights African Easterly waves i.e.Transients 2-6 day band passed precipitation Standard deviation (StDEV) (JAS) Highlights African Easterly waves i.e.Transients

2-6 day StDEV of meridional wind at 850hpa (JAS) ERA-interim underestimates AEW StDEV in precipitation compared to TRMM which suggests that the StDEV in v850 may also be an underestimate in ERA-interim (e.g. RCMs are likely more realistic)

EC-Earth ~1.25° run with prescribed SSTs exhibits the same underestimate of StDEV for precipitation ECEARTH 2.1 has IFS physics almost identical to used in ERA-interim

2-6 day band passed precipitation Standard deviation (StDEV) (JAS) TRMM data averaged to 1.25° and RCA with increasing resolution

Consistent with reduced precipitation StDev compared to ERA-interim meridional wind StDEV at 850hpa is also reduced in EC-Earth

Wind variance is much less sensitive to resolution than precipitation OK. Diabatic heating affects dynamics on a larger spatial scale.

JAS mean diurnal cycle of precipitation (1998-2008) Northern West Africa region

Time of precipitation maximum within the diurnal cycle JAS 1998-2008

Summary CORDEX has now started Africa-CORDEX becoming organized, 13 groups making ERA-interim runs 1989-2008 on a common Grid, 50km grid. An Africa diagnostic & evaluation panel has been formed led by Univ of Cape Town. Euro-CORDEX & Med-CORDEX domains are also organizing. ERA-interim runs at 10km resolution in progress. MPI leads the formation of a European diagnostic/evaluation panel South America CORDEX becoming organized (based around CLARIS) CORDEX ESD group also now forming. 1st CMIP5 boundary data available late 2010. Discussions occurring how best to distribute these along with planning the best approach to filling the multi-dimensional GCM/RCM/ESD/emission matrix An initial CORDEX archive will be available in August at DMI. Discussion with CMIP5 archive centres begun regarding use of ESG