CLIVAR International Climate of the 20 th Century (C20C) Project

1. CLIVAR International Climate of the 20th Century (C20C) Project Jim Kinter, COLA Chris Folland, Hadley Centre, Met Office 4th C20C Workshop, Exeter, UK 13 March 2007

2. C20C Project in the Future: Issues for Consideration • Experimental design • Sharing data and multi-model consensus • Linkage to WGSIP • Decadal prediction • Extension to 1850 • Contributions to AR5 • Publications • Highly encouraged! • Live list compiled: http://www.iges.org/c20c/c20c_related_papers.pdf

3. Experimental Design • Pacemaker • Are additional experimental protocols needed? • Other regions in which to specify time-varying SST • Standard formulation for Q-flux • Dynamical ocean models • Land Use and Change (LUC) • Soil moisture and land use changes sensitivity • LUC in AMIP-type vs. Pacemaker-type format • Experiments w/ and w/o time variation of GHG • WAMME-oriented experiments • Phenomena-Focused Experiments (subsets of C20C group) • West African Monsoon Modeling and Evaluation (WAMME) • Asian monsoon • Influence of the stratosphere on seasonal predictability

4. Sharing Data and Multi-Model Consensus • It is imperative that modeling groups make their data available to all other C20C participants • Modality? (license agreements, co-authorship …) • Technical matters (FTP? GDS? Central archive?) • Some work has already been done on model consensus (Scaife, Kucharski) -- what other systematic efforts should be undertaken?

5. 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 S-I predictions, considering such factors as 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 • How can C20C work together with WGSIP more closely? • Issue: “no cheating” • WCRP Workshop on Seasonal Prediction • Barcelona, Spain, 4-7 June 2007 • http://www.clivar.org/organization/wgsip/spw/main.html • Should C20C and WGSIP extend to decadal prediction in a changing climate?

6. Seasonal to Decadal Prediction • Rigorously defined experiments needed • Investigate mechanisms - do they have a bearing on predictability? • Consistent with "classical" C20C goals: • Determine the extent to which atmospheric models are able to simulate the observed climate variations during the 20th century • Determine potential ability of ensembles of AGCM runs to simulate specific historical events such as regional floods and droughts, the Dust Bowl in North America, the persistent drought in the Sahel and other extremes • Attribute origin of observed climate trends over past century

7. Estimated PDO OBS CGCM Estimated NPO CGCM OBS

8. NP Index Regression: Heat Content And SST Along 42N Heat Content And SST Along 42N and 180 Lag-Lead (years) North Pacific Index = SST Averaged from 150-170 and 40-45N

9. North Pacific Index Idealized Prediction Experiments “Observations” “Observations” Ensemble Predictions Ensemble Predictions Lead Time (months) Lead Time (months)

10. Extension to 1850 • Long-stated goal • How many groups have done this? Plan to do it? • What are the issues w.r.t. the forcing data sets?

11. Contributions to IPCC AR5 • The Intergovernmental Panel on Climate Change (IPCC) has begun to release its 4th Assessment Report (AR4) • C20C is well-positioned to contribute in a major way to AR5, anticipated in 2012-2013 • What specific experiments are needed to get ready for AR5?