Progress on FIM development toward membership in the North American Ensemble Forecast System tp://fim.noaa.gov John M. Brown Stan Benjamin Rainer Bleck Susan Sahm Shan Sun Jian-Wen Bao Tom Henderson James Rosinski Tanya Smirnova Brian Jamison NOAA-Earth System Research Lab Boulder CO Paper 1c2.2 CMOS 2012 Congress / AMS 21 st NWP and 25 th WAF Conferences 29 May – 1 Jun
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Progress on FIM development toward membership in the North American Ensemble Forecast System
Progress on FIM development toward membership in the North American Ensemble Forecast System. John M. Brown Stan Benjamin Rainer Bleck Susan Sahm Shan SunJian-Wen Bao Tom HendersonJames Rosinski Tanya SmirnovaBrian Jamison NOAA-Earth System Research Lab Boulder CO. - PowerPoint PPT Presentation
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Progress on FIM development toward membership in the North
American Ensemble Forecast System
http://fim.noaa.gov
John M. Brown Stan BenjaminRainer Bleck Susan SahmShan Sun Jian-Wen BaoTom Henderson James RosinskiTanya Smirnova Brian Jamison
NOAA-Earth System Research LabBoulder CO
Paper 1c2.2 CMOS 2012 Congress / AMS 21st NWP and 25th WAF Conferences 29 May – 1 Jun 2012
Flow-following- finite-volume
Icosahedral Model FIM
X-section location
Temp at lowest level
Original concept and early work on FIM was by Sandy MacDonald and Jin Lee, ESRL
FIM numerical model•Horizontal grid
• Icosahedral, Arakawa A grid – testing 60km/30km/15km•Vertical grid
NOAA Earth System Research Laboratory - Boulder, Colorado Page 4
• Finite-volume Integrations on Local Coordinate
• Efficient Indirect Addressing Scheme on Irregular Grid MacDonald, Middlecoff, Henderson, and Lee (2010, IJHPC) : MacDonald, Middlecoff, Henderson, and Lee (2010, IJHPC) : A General Method for Modeling on Irregular Grids.A General Method for Modeling on Irregular Grids.• FIM: Hybrid σ-θ Coordinate
- Bleck, Benjamin, Lee and MacDonald (2010, MWR): On the Use of an Arbitrary Lagrangian-Eulerian Vertical Coordinate in Global Atmospheric Modeling.
• Conservative and Monotonic 3rd-ord Adams-Bashforth w/ FCT Scheme- Lee, Bleck, and MacDonald (2010, JCP): A Multistep Flux-Corrected - Lee, Bleck, and MacDonald (2010, JCP): A Multistep Flux-Corrected Transport SchemeTransport Scheme
• Grid Optimization for Efficiency and Accuracy - Wang and Lee (2011, SIAM): Geometric Properties of Icosahedral-Hexagonal Grid on Sphere.
Novel features of FIM:
Lee and MacDonald (MWR, 2009): A Finite-Volume Icosahedral Shallow Water Model on Local Coordinate.
Bisection: N=(2**m)*10 + 2 “m” is any integer ratio between arc A-B (~8000 km) and target resolution. e.g., for dx~20 km, then m=8000/20=400N=(400**2)*10+2~1.6 million points.FIM – Ning Wang (ESRL) Can use arbitrary sequence of bisections and trisections
Sadourny, Arakawa, Mintz, MWR (1968)
Construction of an icosahedral grid high granularitypossible with icosahedral model
ikl ,
ikn ,
The 2-D operator applied to the straight lines, rather than the 3-D operator along the curved lines, e.g.,
Stokes’ theorem:
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Local stereographic projection for each icosahedral grid volume for local geometry
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Fqs
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FIM governing equations and solution procedure
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FIM design – vertical coordinateHybrid (sigma/ isentropic) vertical coordinate Improved transport by reducing numerical dispersion from vertical cross-coordinate transport, improved stratospheric/tropospheric exchange.
• Used in NCEP Rapid Update Cycle (RUC) model
• Used in HYCOM ocean model
Installed as generalized “s” vertical coordinate - can be replaced with GFS sigma-p or other coordinates.
Staggering of variables in layer or stacked shallow-water models: Used in FIM
FIM vertical coord hybrid σ-θ-σ option
•2 σ layers at top
•θv reference values for all levels
•σ layers at surface set at max=15 hPa
θ-σ
(~zero in fixed
grids)
(~zero in material coord.)
(known)
Continuity equation in generalized (“s”) coordinates
Initial Physics in FIMGFS physics
• Immediate goal for FIM is contributing dynamical-core diversity to NCEP Global Ensemble Forecast System
• Use of current GFS physics (Fanglin Yang’s talk 1B1.2, previous session) allows evaluation of differences between GFS and FIM dynamical cores.
Application of GFS physics to FIM
• No changes needed to physics for hybrid θ-σ application with one exception: mod to avoid negative mass flux in deep/shallow cu, no change to GFS performance
• Applied every 180s (multiple explicit time-steps in FIM)
Current retrospective experiments with Grell-3D replacing GFS deep/shallow cumulus
Key Recent FIM Changes April 2011
Fix to FCT numerics (error in high-order fluxes) Nov 2011
Upgrade from GFS 2010 physics to May-2011 GFS physics
Addition of icosahedral momentum diffusion (upgraded to 4th order April 2012)
Currently working on upgrade to May 2012 GFS physics (major code upgrade; only minor changes to actual physics)