An examination of FIM performance for a variety of weather scenarios

Over the last year considerable effort has been made at ESRL to develop and test a new global model that includes unique features, such as use of the adaptive isentropic-sigma hybrid vertical coordinate successful with the RUC model, accurate finite-volume horizontal advection, and an icosahedral horizontal grid. The model has been named the FIM, for Flow-following finite-volume Icosahedral Model. It is currently being run twice per day at ESRL/GSD out to 168 hours at a horizontal grid resolution of approximately 30 km. Initial conditions at 0000 and 1200 UTC for these real-time runs are those from the Global Forecast System (GFS) for the Global Spectral Model, and the physics package being used for these runs is that of the GFS.

There are several long term goals for the FIM, but one includes the possibility that it may become a member of the North American Ensemble Forecast System. With this in mind, part of our assessment activities have included examination of the model forecasts for various weather scenarios over different seasons. Comparison has been made with the forecasts from other operational global models, including the GFS model. While a number of our cases focus on North American weather systems, we have also looked at forecasts from around the globe. Some of the cases have been identified by looking for outlier events (e.,g., "dropouts") identified through anomaly correlation scores of the 500 mb height forecasts. At the conference we will discuss a representative selection of the cases we have examined.