An Examination of FIM Performance For A Variety of Weather Scenarios

Abstract

Over the last year considerable effort has been made at the Earth Systems Research Laboratory (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, and is currently being run twice per day at the Global Systems Division (GSD) of ESRL. 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 (NAEFS). 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 Global Forecast System (GFS) model and the long-range model of the European Centre for Medium-Range Weather Forecasts (ECMWF). While a number of our cases focus on North American weather systems, we have also looked at forecasts from around the globe. If the FIM model is to become part of the NAEFS it is important to gain an understanding of the reliability of the model forecasts and how they compare to other global models. Our efforts in this regard are summarized in this paper, with an overview of FIM performance followed by a look at a few representative cases.