Hadley Centre © Crown copyright 2004 The CLIVAR International Climate of the Twentieth Century...

© Crown copyright 2004

Hadley Centre

The CLIVAR International Climate of the Twentieth Century (C20C) Project

1. History and aims

2. Methodology and approach

3. Forcing data sets

4. Some achievements

5. Future development of C20C and issues

Chris Folland, Hadley Centre, Met Office & Jim Kinter, COLA

4th Climate of the Twentieth Century Workshop, Exeter 13- 15 March , 2007


Hadley Centre

Purpose and basic methodology

Initially focused on AGCMs all forced with same HadISST sea surface temperature and sea ice analysis

Characterize variability, trends and predictability of climatic conditions and events of the past ~130 years associated with various slowly varying forcing functions including SST

Differs from AMIP in NOT being primarily focused on model validation and with strong multi-annual to multi-decadal variability (predictability and understanding aspects) focus. AMIP only c. 20 years, C20C 130 years.


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Approach

Period of interest: 1871-currentOrganization:Jointly organized by Hadley Centre, UK & Center for Ocean-Land-Atmosphere Studies (COLA), USA24 different modeling groups participating internationally CLIVAR project & reporting to WMO/CAS/WGNE

Now includes many other forcing data sets, including greenhouse gases, ozone, volcanic aerosols and solar variability, but not uniformly across groups yet.Now expanded to include use of “Pacemaker experiments” and coupled models in order to more accurately simulate modes of variability that are inherently coupled and to understand mechanisms.


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Contributions of C20C

C20C contributes to:

Seasonal to interannual predictability

Decadal to interdecadal variability & predictability

Understanding climate trends

Model evaluation


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Chronology

Project initiated by Hadley Centreseveral informal bilateral collaborations established1st workshop held at Hadley Centre in Nov 1994Input to 1995 IPCC assessment and special session at 1st international AMIP conference in 1995

Revitalized by Hadley Centre with strong COLA infrastructure support.1998 invitation to several modeling groupsinfrastructure provided by COLA (www.iges.org/c20c; GDS) 2nd workshop held at COLA in Jan 2002 (reported in CLIVAR Exchanges, Jun 2002)Agreed set of runs with updated forcing data sets, diagnostics and special projects

C20C established as official CLIVAR project in January 2003Third Workshop - 19-23 Apr 2004, ICTP, ItalySpecial Meeting July 2005, Prague, Czech Republic


Hadley Centre

Phases of C20C activity since 1999

Phase 1 (prior to 2003): SST and sea ice changesHadley Centre provides HadISST1.1 SST and sea ice data set as lower boundary conditions Integrate over 1871-2002 (at least 1949-2002)Ensembles of at least 4 members

Phase 2 (2003 - ): include atmospheric composition changesGreenhouse gases – CO2, O3, etc. Aerosols (volcanic)Solar variabilityHadley Centre can provide a full set of forcings

Phase 3 (2007 - 2011): “Pacemaker” experiments, much more emphasis on land surface /diurnal variation of SST/ better SST and sea ice

Land surface forcing (version already in Hadley Centre model) and special experiments Explore influence of diurnal variation of SST in HadiSST1 More highly resolved HadISST2 from 2009.


Hadley Centre

Special Topics

Predictability and understanding of seasonal to multi-decadal phenomena 1930s drought in USA (“Dust Bowl”) 1962-63 European winter (links to NAO time series work) Autumn 2000 western European floods 2003 European heat wave Interdecadal variations of summer climate over Europe and North Atlantic. Decadal modulation of responses to ENSO

Time series – variations, trends and their causesSOI, NAO, PNA, Asian monsoon rainfall, Sahel rainfall, Nordeste of Brazil rainfall, MJO trendsGlobal and regional land surface air temperature trends

Others, e.g., river runoff trendsUse of new diagnostic methods in climate variability studies


Hadley Centre

Key Validating Data Sets

NCEP/NCAR Reanalysis (1948-now)

ERA40 Reanalysis (1958-2002)

HadSLP global monthly sea level pressure analysis updated with modified NCEP (1871-2007)

New EMSLP daily sea level pressure data set over extratropical N Atlantic and Europe 1871-2003

Brohan et al land surface air temperature data (1850- now) and Hulme land surface rainfall analyses (1871-now)

Xie-Arkin global precipitation analysis (1979-now)


Hadley Centre

Report of the C20C Prague Special Meeting, 2005


Hadley Centre

Key Proposals of the 2005 Prague Special Meeting for future coordinated C20C experiments


Hadley Centre

Links to WCRP

C20C became a CLIVAR activity in Jan 2003

Also reports to Working Group on Numerical Experimentation (WCRP/CAS/WGNE)

Need to strengthen our links to the Working Group on Seasonal to Interannual Prediction. How should we do this? Exploratory meeting involving CKF in autumn 2004.


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Three contrasting examples of recent

C20C published papers


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from Schubert et al. 2004 (Science, 19 Mar2004)

Simulating Dust Bowl era drought


Hadley Centre

Effect on the winter NAO of imposing observed stratospheric

winds at 50hPa on HadAM3

Change in NAO index Change in surface pressure

Model also forced with HadISST and all known major forcings in C20C mode.

Full NAO and surface climate change 1965-95 reproducedFrom Scaife et al, 2005, GRL


Hadley Centre

Secular increase in predictability of boreal winter mean temperature over land, 1897-1998, using two models mainly caused by decadal changes in ENSO variability

Kang et al, 2006, GRL, highlighted

Hadley Centre © Crown copyright 2004 The CLIVAR International Climate of the Twentieth Century...

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