The World Climate Research Program (WCRP) Working Groups on Seasonal to Interannual Prediction (WGSIP) and the Working Group on Climate Modelling (WGCM) are organizing an international workshop on seasonal and decadal prediction. The workshop will be held in Toulouse, France, from 13 to 16 May 2013, under the sponsorship of Météo-France, CNRS, CERFACS, WCRP, NOAA and the fundation BNP-Paribas.

Workshop on Seasonal to Decadal Prediction

The goal of the workshop is to review our current abilities to make skillful predictions on seasonal to decadal (s2d) timescales. The availability of results from the Climate system Historical Forecasting Project (CHFP) and the decadal prediction component of the Coupled Model Intercomparison Project (CMIP5), together with very active investigations in both operational and research communities, support the timeliness of the Workshop. Areas of interest include :

Predictability. Studies of where, and to what extent, skillful s2d predictions may be possible and the associated physical mechanisms. Initialization and ensemble generation. The information that is needed to enable prediction on different timescales and the availability and nature of this information for initializing past and current forecasts. Methods of initialization and their effects including full-field and anomaly initialization. The generation of the ensembles needed to characterize the probability distribution of forecasts. Models. The main deficiencies of current coupled models as they affect s2d predictive skill and the prospects for improvement. Information about models that forecast results reveal and the trade-off between resolution, model complexity and ensemble size. The status and use of statistical models for s2d prediction. Bias adjustment, calibration and combination of forecasts. Methods of postprocessing s2d predictions from models including bias adjustment, forecast calibration, multi-model combination etc. The statistical considerations involved in these methods. Forecast quality. Measures of forecast skill and value which are useful and appropriate at s2d forecast ranges. Metrics which asses the contributions of external forcing and initialization to forecast skill, which guide forecast development, suggest regions and mechanisms of untapped skill, and which may be used to assess improvements in prediction methods. Applications. The success and utility of modestly skillful predictions across the s2d timescales. The contributions of s2d forecasts to Climate Services.

A Workshop report will summarize the results and expert opinions on the topics presented and will contribute to Frontiers 1 and 2 of the WCRP Grand Challenge #1 dealing with Regional Climate Information.