Progress in Development of the Flow-Following Finite-Volume Icosahedral Model (FIM) Toward Improving NCEP Global Ensemble Forecasts and Toward a Chemistry-Coupled Global Model Research Capability
In this presentation, we will focus on improvements to the FIM since June 2009, including those in physics, vertical coordinate, and inline chemistry with treatment of volcanic ash. After a very brief review of the numerical characteristics of the FIM model [isentropic-sigma-hybrid vertical coordinate, finite-volume (FV) transport, icosahedral horizontal grid], we will include comparison of forecast skill between the FIM model and NCEP's GFS model.
Recent improvements in the vertical coordinate have enhanced robustness of the FIM in flow features, especially in the stratosphere and lower mesosphere. A new physical parameterization package from the GFS (implemented in NCEP GFS in late July 2010) has also been successfully implemented within the FIM (results to be shown). NOAA/ESRL has also extended the FIM to an inline-chemistry version with 16 aerosol types, including 4 size bins for volcanic ash. This FIM-chem-ash version resulted from the incorporation of a version of the WRF-chem package within the FIM framework, with transport of all aerosols within the FIM isentropic-FV-icosahedral framework. The FIM-chem-ash model was implemented in response to the April 2010 volcanic eruption of Eyjafjallajokull in Iceland.
Future plans for the FIM will be described, including incorporation of its dynamic core within NCEP's Global Ensemble Forecast System, and application of FIM-chem-ash for NOAA research issues.