1. 2014 Sea ice prediction workshop Michael Sigmond Canadian Centre for Climate Modelling and Analysis

2. Overview 2 day workshop at NCAR, ~70 participants interested in seasonal predictions of sea ice SIPN: multi-agency 5-year funded US project Emerging and rapidly evolving field Dynamical models: CanSIPS, NCEP, Meteo- France, Met-Office, GFDL, NASA, EC- EARTH)

3. Study of Environmental ARctic Change (SEARCH) Has collected forecasts for September sea ice area since 2008 Sept 2011 Sept 2012 (actual) Statistical Dynamical Heuristic Combination of methods

4. Study of Environmental Arctic Change (SEARCH) Emerged in response to need to increase understanding following unexpected 2007 record low minimum Forum to discuss physical mechanisms that influence summer sea ice loss Not a replacement of forecasts by national centres like CIS, NIS

5. WORKSHOP GOALS 1)Make recommendations for SEARCH 2)Advance science by coordinating MIPS 3)Develop datasets for initialization and validation 4)Create new and better metrics for evaluation 5)Discuss stakeholder needs and communication

6. Historical performance SEARCH -Bimodal success -Deviations from trend hard to predict Stroeve et al. (Geophys. Res. Lett., 2014) Observed deviation from trend Observed minus forecast

7. SEARCH recommendations -Keep as research project, while providing real time data and post-season analysis -Future: explore more regional forecast and probabilistic forecast Note: CanSIPS contribution problematic as hindcasts and forecasts are not initialized with same dataset

8. Potential predictability -What is the limit of predictability? -Sources of prediction error: 1) imperfect knowledge initial conditions 2) model error 3) unpredictable (weather) noise - Perfect model: use model to predict itself

9. Potential predictability discussion -MIP on potential predictability (APPOSITE) -Have we reached limit of predictability? -Role of initialization of sea ice (extent versus thickness), ocean? -Seasonal dependency of skill? -Are extreme years less predictable? -Will predictability change in the future?