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

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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. Continuing development of C20C

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

West African Monsoon Modeling and Evaluation (WAMME) Workshop - 20 January 2008 - New Orleans


Hadley Centre

Purpose and basic methodology

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

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

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 ~20 years C20C: ~130 years


Hadley Centre

Approach

Period of interest: 1871-current

Organization: Jointly organized by Hadley Centre, UK & Center for Ocean-Land-Atmosphere Studies (COLA), USA 28 different modelling groups participating/affiliated internationally CLIVAR project & reporting to WMO/CAS/WGNE

Now includes many other forcing data sets, including greenhouse gases, ozone, volcanic aerosols and solar variability

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


Hadley Centre

Contributions of C20C

C20C contributes to:

Seasonal to interannual predictability

Decadal to interdecadal variability & predictability

Understanding climate trends

Model evaluation


Hadley Centre

Chronology

Project initiated by Hadley Centre 1993 several informal bilateral collaborations established

1st workshop - Hadley Centre Nov 1994 input to 1995 IPCC Assessment chapter “Climate Models – Evaluation”. special session at 1st international AMIP conference in 1995

Revitalized in 1998-9 through infrastructure provided by COLA (www.iges.org/c20c; GDS)

2nd workshop - COLA Jan 2002 reported in CLIVAR Exchanges, Jun 2002 agreed set of runs, updated forcing data sets, diagnostics and special projects


Hadley Centre

Chronology

C20C established as official CLIVAR project in January 2003

3rd workshop - 19-23 Apr 2004, ICTP, Italy

Special meeting - 4-5 July 2005, Prague, Czech Republic reported in CLIVAR Exchanges, Oct 2006

4th workshop - 13-15 March 2007, Hadley Centre, UK reported in CLIVAR Exchanges, Jan 2008


Hadley Centre

Phases of C20C activity since 1999

Phase 1 (prior to 2003): SST and sea ice changes Hadley 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 changes Greenhouse gases – CO2, O3, etc. Aerosols (volcanic) Solar variability Hadley Centre can provide a full set of forcings inc. HadISST almost to date.

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 enhanced version of HadISST1 More highly resolved HadISST2 from late 2009 based partly on the new high resolution Met Office OSTIA data set now used in NWP.


Hadley Centre

C20C Participating Groups

BOM (Australia)COLA + GMU (USA)CERFACS (France)CNRM (France)CPTEC (Brazil)ETH Zurich (Switzerland)Hadley Centre (UK) IPSL (France)LASG/IAP (China) ICTP (Italy) INGV (Italy)

MIT (USA)MRI/JMA (Japan)NASA/GMAO (USA)NIWA (New Zealand)GFDL (USA)PMOD/WRC (Switzerland)SNU (Korea)UCLA (USA)UMCP (USA)MGO (Russia)


Hadley Centre

Links to WCRP

C20C reports to CLIVAR including reports in CLIVAR Exchanges

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

New Links to CLIVAR/SPARC.


Hadley Centre

Linkage to WGSIP

WMO/WCRP Working Group on Seasonal to Interannual Prediction (WGSIP) works in C20C-related areas

develop a program of numerical experimentation for S-I variability & predictability, paying special attention to assessing & improving predictions

develop appropriate data assimilation, model initialization & forecasting procedures for seasonal to interannual predictions, considering factors like observing system evaluation, use of ensemble & probabilistic methods and statistical and empirical enhancements

advise CLIVAR SSG on the status of S-I forecasting & adequacy of CLIVAR observing system, and liaise with JSC/CLIVAR WGCM and JSC/CAS WGNE

C20C - WGSIP collaboration discussed at WCRP Workshop on Seasonal Prediction (Barcelona, Spain, 4-7 June 2007)


Hadley Centre

Contributions to IPCC AR5

C20C is well-positioned to contribute in a major way to Intergovernmental Panel on Climate Change (IPCC) AR5, anticipated in 2012-2013

Detailed input planned at next Workshop late 2009 when IPCC AR5 will be clearer


Hadley Centre

Special Topics

Predictability and understanding of seasonal to multi-decadal phenomena 1930s drought in USA (“Dust Bowl”) Winter NAO variations, especially since 1960 including stratospheric influences. Autumn 2000 western European floods 2003 European heat wave Interannual to interdecadal variations of summer climate over Europe and North Atlantic. Decadal modulation of responses to ENSO

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

Others, e.g., river runoff trends Use 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 (1850-2007)

New EMSLP daily sea level pressure data set over extratropical N Atlantic and Europe (1850-2003)

Brohan et al land surface air temperature data (1850- now) and Hulme land surface rainfall analyses (1871-1998)

Xie-Arkin global precipitation analysis (1979-now)


Hadley Centre

Recently designed C20C experiments


Hadley Centre

Three contrasting examples of recent C20C published papers

List of contributions: http://www.iges.org/c20c/c20c_related_papers.pdf


Hadley Centre

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

Evolving C20C Experimental Design

Pacemaker Specified SST in limited region (e.g. eastern tropical Pacific or north Atlantic)

Thermodynamic ocean (slab or mixed layer formulation with Q-flux)

Dynamical ocean models in some basins Land Use and Change (LUC) Coordination with LUCID

Phenomena-Focused Experiments subsets of C20C group

West African Monsoon Modeling and Evaluation (WAMME)

Asian monsoon

Influence of the stratosphere on seasonal predictability

Use of fully coupled models for investigating near century phenomena like AMO


Hadley Centre

Pacemaker Strategy: Overcoming Shortcomings of AGCMS and Coupled Models

The “Pacemaker” strategy permits a consistent air-sea energy balance while simultaneously including the time sequence of climate-driver events, such as ENSO.

Teleconnections from the eastern tropical Pacific to remote tropical and extratropical regions are well represented in pacemaker runs, e.g., phenomena that are at once driven by and independent of ENSO,

like the Asian monsoon.

DJF SST Composite (El Nino - La Nina)

Observed

Pacemaker

PacemakerObserved

JJA Rainfall Composite (El Nino - La Nina)

Cash et al. 2007

Pacemaker design: specified SST

regions


Hadley Centre

Conceptual model for analysis of ensembles

20th Century ClimateEvent

(e.g. surface T trend)

Consistent with ensemble means?

Potentially predictable,“forced” and well

modelled

Consistent withensemble members?

Unpredictable internal variation but well

modelled

Poorly modelled in thisexperiment:

missing process/forcing

YES

NO

NO

YES

Methodology for multi-model evaluation (Scaife et al. 2008 in prep.)


Hadley Centre

Simulations of climate indices(Scaife et al, in prep)


Hadley Centre

Simulation of Indian Monsoon Rainfall (IMR) and causes of its decadal variations – Kucharski et al in prep.

Interannual ensemble means, ENSL (1902-1999; black) and CRU (red)

Interannual ensemble means, ENSS (1950-1999; black) and CRU (red)

Decadal IMR of CRU (red) and the ensemble means of C20C (black)

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

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