International C20C Project: History and Overview

1. International C20C Project: History and Overview J. Kinter, C. Folland and F. Molteni Third International C20C Workshop 19 April 2004 ICTP - Trieste, Italy

2. Background • Purpose: Characterize variability and predictability of climatic conditions and events of the past ~130 years associated with various slowly varying forcing functions • Initially focused on AGCMs forced with HadISST sea surface temperature and sea ice analysis

3. Example: Excerpt from Schubert et al. 2004 (Science, 19Mar2004)

4. Background (continued) • Period of interest: 1871-current • Organization: • Jointly organized by Hadley Centre, UK & Center for Ocean-Land-Atmosphere Studies (COLA), USA • 15 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 • Being expanded to include use of coupled models in order to more accurately simulate modes of variability that are inherently coupled

5. Current Participating Groups • Bureau of Meteorology, Australia (www.bom.gov.au) • China Meteorological Agency, China (www.cma.gov.cn) • Center for Ocean-Land-Atmosphere Studies, USA (www.iges.org) • Centro de Previsão de Tempo e Estudos Climáticos, Brazil (www.cptec.inpe.br) • Department of Natural Resources, Mines & Energy, Queensland, Australia (www.nrm.qld.gov.au) • NASA Goddard Space Flight Center, USA (gmao.gsfc.nasa.gov) • Hadley Centre, Met Office, UK (www.metoffice.com/research/hadleycentre) • International Centre for Theoretical Physics, Italy (www.ictp.trieste.it) • MeteoFrance, France (www.meteo.fr) • Main Geophysical Observatory, Russia (www.mgo.rssi.ru) • Meteorological Research Institute, Japan (www.mri-jma.go.jp) • National Institute for Environmental Studies, Japan (www.nies.go.jp) • National Institute of Water and Atmospheric Research, New Zealand (www.niwa.cri.nz) • Seoul National University, Korea (www.snu.ac.kr:) • University of California at Los Angeles, USA (www.ucla.edu)

6. Chronology • Project initiated by Hadley Centre • several informal bilateral collaborations established • 1st workshop held at Hadley Centre in Nov 1994 • Input to 1995 IPCC assessment and special session at 1st international AMIP conference in 1995 • Revitalized by Hadley Centre and COLA • 1998 invitation to several modeling groups • infrastructure 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 2003 • Third Workshop - 19-23 Apr 2004, ICTP, Italy

7. Contributions C20C contributes to: • Seasonal to interannual predictability • Decadal to interdecadal variability & predictability • Simulations of climate trends • Model evaluation

8. Special Topics • Predictability of seasonal to decadal phenomena • 1930s drought in USA (“Dust Bowl”) • 1962-63 European winter • Autumn 2000 western European floods • 2003 European heat wave • Decadal modulation of response to ENSO in Australia, Indian monsoon • Time series and trends • SOI, NAO, PNA, Asian monsoon rainfall, Sahel rainfall, Nordeste Brazil rainfall, MJO trends • Global and regional land surface air temperature trends • Others, e.g., river runoff trends

9. Validating Data Sets • NCEP/NCAR Reanalysis (1948-2003) • ERA40 Reanalysis (1958-2002) • HadSLP global sea level pressure analysis (1871-2002) • Jones land surface air temperature and Hulme land surface rainfall analyses (1871-2002) • Xie-Arkin global precipitation analysis (1979-2003)

10. Diagnostics • Monthly means, all ensemble members • Geopotential height at 500 and 200 hPa • Mean sea level pressure • Precipitation and evaporation • Temperature at 2m and 850 hPa • Zonal and meridional winds at 850 and 200 hPa • Total heat flux and wind stress • Soil moisture index • Zonal mean cross-sections of U, V, T and q • Basic statistics • Seasonal means and standard deviations • Estimates of forced variability (ANOVA) • Linear regression trends 1950-1999 (or 1952-2001) • Regression with NINO3.4 • Special diagnostic projects • {Refer to Second C20C Workshop, Working Group 2 Report}

11. Links to CLIVAR • C20C became a CLIVAR activity in 2003 • Also reports to Working Group on Numerical Experimentation (WCRP/CAS/WGNE) • Exploring links to WCRP Working Groups on Seasonal to Interannual Prediction (WCRP/CLIVAR/WGSIP) and Coupled Modeling (WCRP/CAS/WGCM)

12. C20C Phases of Activity • Phase 1 (prior to 2003) : SST and sea ice • 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 - ) : atmospheric composition • Greenhouse gases – CO2, O3, etc. • Aerosols (volcanic) • Solar variability • Phase 3 (2004 - ) : land surface variability • specified evolution of soil wetness and vegetation

13. Current Activities • Third Workshop • 19-23 April 2004; hosted by ICTP (Trieste, Italy) • Results of Phase 1 integrations; initial Phase 2 results • Planning for Phase 2 and beyond • Representatives of WCRP programs – discussion of how to specify/deal with forcings, coupled models • Planning for comparison to coupled models • Coupling to mixed layer or dynamical ocean • Coordination with WGCM • Efficient estimation of anthropogenic signals

14. Issues • What are the limitations of AGCM runs that have no direct coupling to the ocean surface? Are local/regional fluxes misleading? • How should we include coupled models in C20C work, e.g. thermohaline-forced variations in climate? understanding interannual predictability? • Should we adopt a set of common or core diagnostics that all groups will produce in order to contribute to the IPCC assessment (model evaluation) in a more systematic way?

15. Future … • Report of Third Workshop to CLIVAR 2004 Conference in June 2004 • Input to model evaluation or other relevant sections of 2005 IPCC assessment • Fourth C20C Workshop in 2006 tentatively being planned for Exeter, UK