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Development of The FIM (flow-following FINITE-VOLUME Icosahedral Model) Global Model Toward An Earth System Model Including Inline Treatment of Aerosols and Trace Gases


Development of the FIM, ESRL’s new global model, is now being extended beyond medium-range weather forecasts to include aerosols and trace gases. The FIM uniquely combines 3 key modeling design components (icosahedral horizontal grids, isentropic-hybrid vertical coordinate, finite volume numerics), all critical to provide improved transport over existing models (e.g. Global Forecast System – GFS). The isentropic-hybrid vertical coordinate is “flow-following” in that the vertical coordinate surfaces follow isentropic (constant potential temperature) surfaces through most of the atmosphere, from mid-troposphere upward to the model top (current testing at ~60 km). This design greatly reduces cross-coordinate transport and resulting artificial numerical dispersion over that in most other atmospheric models. Atmospheric forecasts from the FIM now generally match those from the NCEP GFS model, necessary for planned inclusion of FIM as part of NCEP’s Global Ensemble Forecast System. The FIM-chem inline coupled model is now in development, starting with a simple aerosol model from the GOCART including a global emissions inventory. (demo FIM-chem 3-day forecast in figure below). ESRL scientists from all four divisions are planning toward extension of FIM-chem to add trace gases, and also working toward a possible ocean component, and new land-surface, cloud, and boundary-layer parameterizations. This gives FIM potential for becoming an Earth Systems Model research tool, as well as having a real-time prediction capability. Figure

Article / Publication Data
Available Metadata
Fiscal Year
Published On
May 01, 2009
Submitted On
May 16, 2009

This publication was presented at the following:

ESRL Global Monitoring Annual Conference
ESRL/Global Monitoring Division
Conference presentation


Not available


Authors who have authored or contributed to this publication.

  • Andrew R. jacobson - Not Positioned Gml
    Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder
    NOAA/Global Systems Laboratory