The IERS Earth Orientation Parameters Combination of Prediction Pilot Project (EOPCPPP) B. Luzum (U.S. Naval Observatory), W. Kosek (Space Research Centre), N. Shumate (USNO), M. Kalarus (SRC) Abstract. Ensemble predictions make use of sampling the “prediction space” by using various algorithms and potentially different, but still likely, initial conditions. By producing different predictions and combining the results, these ensemble predictions are more accurate than the results from individual predictions. The IERS has initiated a pilot project to determine the feasibility of combining EOP predictions on an operational basis. To date, the project has nine EOP prediction contributors with three of these contributors also planning to produce ensemble EOP predictions. Auxiliary data sets are also being studied to determine their potential contribution to the project. Initial findings from the EOPCPPP will be reported and future plans will be discussed. Contributions: Jet Propulsion Laboratory, Paris Observatory (2 solutions),PulkovoObservatory (2 solutions), Shanghai Astronomical Observatory, Siberian Scientific Research Institute of Metrology (2 solutions), Space Research Centre, Sternberg Astronomical Institute, Ulyanovsk State Technical University, U.S. Naval Observatory Auxiliary Data Sets: GeoForschungZentrum EAM 10-day forecasts, IGS Ultra-rapid predictions Combined Predictions: Pulkovo Observatory, Space Research Centre, U.S. Naval Observatory Red denotes series under development Background. Ensemble predictions are a practical extension of the Central Limit Theorem. The concept of ensemble predictions has been used in weather forecasting for at least 15 years and has reached a state of maturity such that most of the major weather forecasting organizations utilize ensemble predictions to some degree. Ensemble predictions make use of sampling the “prediction space” by using various algorithms and potentially different, but still likely, initial conditions. By producing different predictions and combining the results, the results of ensemble predictions are more accurate than the results from individual predictions. It is a logical extension to consider the viability of ensemble predictions for Earth orientation parameters. Theoretically, ensemble predictions can improve both the accuracy and the robustness of predictions. This concept has been proposed and tested (Luzum et al., 2007) and initial results look promising (Kalaruset al. 2010). This pilot project will determine the feasibility of combining EOP predictions on a daily basis. Above is a partial web page with the information regarding some of the contributed predictions. In addition to contact information, references to methodology is crucial so that those generating ensemble predictions will have algorithm specifications they need to make decisions about combining data. Below is a partial web page of the cumulative statistics of prediction quality, updated daily, that are also of potential use to the combination of predictions. To the right, an example of the plots of cumulative statics that are updated daily. Plots for polar motion y and for UT1-UTC are also updated daily. See the page at the lower left for access to the plots. Near Future. It is expected that the input prediction series that are under development will be completed soon. With their completion, a more thorough investigation into combined prediction series will be possible. Several features are in the process of development In an effort to provide additional tools for use by participants. A summary page will be included to provide feedback to participants by making them aware of issues that have been detected with their prediction series. This feedback will allow participants to modify more quickly their prediction processes, thereby generating more robust prediction content. Ultimate goal: The Pilot Project will determine the feasibility of producing ensemble predictions on a daily basis and to analyze the efficacy of these ensemble predictions. Based on the results of the Pilot Project, recommendations will be made to the IERS Directing Board. It is expected that these recommendations will be provided in Fall For additional information, please see: or If you are intereted in participating in the Pilot Project, please contact: References Kalarus, M., Schuh, H., Kosek, W., Akyilmaz, O., Bizouard, Ch., Gambis, D., Gross, R., Jovanovic, B., Kumakshev, S., Kutterer, H., Ma, L., Mendes Cerveira, P.J., Pasynok, S., Zotov, L., 2010, “Achievements of the Earth Orientation Parameters Prediction Comparison Campaign,” J. of Geodesy, Vol. 84, pp. 587−596, doi /s Luzum, B., Wooden, W., McCarthy, D., Schuh, H., Kosek, W., and Kalarus, M., 2007, “Ensemble Prediction for Earth Orientation parameters,” EGU General Assembly, EGU Abstract: EGU2007-A