West African Monsoon Modeling and Evaluation (WAMME) Workshop - 20 January 2008 - New Orleans. The CLIVAR International Climate of the Twentieth Century (C20C) Project. Chris Folland, Hadley Centre, Met Office & Jim Kinter, COLA. 1. History and aims 2. Methodology and approach - PowerPoint PPT Presentation
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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
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
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
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.
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)
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
Secular increase in predictability of boreal winter mean temperature over land, 1897-1998, using two models mainly caused by decadal changes in ENSO variability
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,