Understanding SREF Ensemble Behavior Using the Method for Object Based Diagnostic Evaluation (MODE)

The Developmental Testbed Center (DTC) ensemble team has recently performed experiment to evaluate the impact of increasing the resolution of the National Center for Environmental Prediction/Environmental Modeling Center (NCEP/EMC) Short-Range Ensemble Forecast (SREF) system from 16 to 9 km. Traditional statistics like the Brier Score, reliability diagrams, rank histograms, and spread-skill were all used to examine the probability fields and the impact of the individual members. Traditional categorical and continuous statistics were also calculated for the ensemble mean. These measures will be used briefly to demonstrate ensemble behavior to be explored further.

This talk then breaks out of the traditional metrics box and looks at the use of spatial metrics defined by the Method for Object-Based Diagnostic Evaluation (MODE) contained in the DTCs Model Evaluation Tools (MET) for diagnosis and evaluation of ensembles. It will use data sets from the DTC SREF testing and evaluation activity and explore the use of MODE on both ensemble means and individual members to better understand ensemble performance, such as over- and under-dispersive behaviors. It will also demonstrate the use of MODE on probabilistic fields and explore how to interpret the results.