The FIM Model
NOAA/ESRL scientists have developed an initial version of a new global model including use of the adaptive isentropic-sigma hybrid vertical coordinate successful with the RUC model, accurate finite-volume horizontal advection, and use of an icosahedral horizontal grid. ESRL is collaborating with NCEP/EMC on ESMF-compatibility of the FIM model, and was aided by GFDL on its initial design.
Three unique features of the FIM
- icosahedral horizontal grid, mostly hexagons except for 12 pentagons ("I" in FIM)
- isentropic-sigma hybrid vertical coordinate, adaptive, concentrates around frontal zones, tropopause, similar to RUC model ("F" for Flow-following in FIM)
- finite-volume horizontal transport (Also under "F", for "finite-volume" in FIM)
News Items
- 30 Dec 2008 Introduced momentum damping for winds > 100 m/s above 5 hPa, found to be necessary after seasonal changes began to develop polar-night jets. (r487)
- 25 Nov 2008 Snow accumulation at surface added, less noise (vertical adjustment) (FIM r456)
- 17 Nov 2008 Correction to atmospheric radiation time error (significantly improves 12z init FIM forecasts). Shallow convection added on 10 Nov.
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5 Nov 2008
64-level version introduced with pressure-top at 0.1 hPa
(previous - 50-level with ptop at 20 hPa).
Also added accurate use of sea-ice fraction.
(FIM r392).
- 17 Oct 2008 Important FIM changes for GSD-FIM30(G8) and TACC-FIM15(G9) runs as of today: Fix to initial height problem, now using initial cloud/condensate fields from GFS, physics called now every 3 min (less frequently but matching GFS), run time reduced 20-25%. (FIM r383).
- 7-9 Oct 2008 Isentropic-Hybrid Modeling Workshop - NOAA/ESRL
- 22 Sept 2008 15km FIM global model runs out to 10-day duration since 28 Aug, output every 3h - Real-time products here. - Status here. Twice daily forecasts run on TACC (Texas Area Computing Center) supercomputer as part of NOAA-TACC demonstration for improved hurricane forecasts.
- 30 Aug 2008 Two key problems fixed for FIM over last 9 days, one concerning interpolation of GFS initial conditions to the FIM grid (fixed 22 Aug), and one concerning initializing soil moisture (fixed 28 Aug). Both of these bugs were significant. (FIM r317) Also, regional output is now available for the western Pacific . .
- 17 July 2008 Regional products added for Arctic and western N. Atlantic . Also, sensible and latent heat flux products added for all global and regional plot domains.
- 2 July 2008 Regional products now available for Africa and CONUS . Other regions under development.
- 2 July 2008 Output redesign for FIM model for isobaric grids on icosahedral grid
- 4 June 2008 Error in land-surface specification corrected.
- Drying trend in forecasts removed
- Improved overall forecast skill
- 8 May 2008 Twice-daily forecasts now out to 168 h (7 days) since late April.
- 17 April 2008 Virtual temperature effect added to calculation of pressure gradient. Prognostic temperature variable is now virtual potential temperature. Average global precipitation and mean zonal wind at jet level increased by about 10% in spring 2008 cases. Change made on 15 April.
- 8 April 2008 Real-data FIM forecasts started in Feb 2008. Graphics here.
- GFS initial conditions, interpolated from GFS spectral data for analysis
- 30km horizontal resolution for FIM runs
- 50 vertical levels (changed to 64 levels with ptop = 0.1 hPa - 5 Nov 2008)
- Use of GFS physical parameterizations (other options to be added including WRF physics options and WRF-chem as a further option)