NCEP ESMF GFS Global Spectral Forecast Model

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NCEP ESMF GFS Global Spectral Forecast Model

• Weiyu Yang, Mike Young
• and Joe Sela
• ESMF Community Meeting
• MIT, Cambridge, MA
• July 21, 2005

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The Version of the NCEP ESMF GFS System

• The NCEP ESMF GFS global spectral forecast system
  is the ESMF version of the current NCEP
  operational GFS system which started its
  operational run on May 31, 2005.
• The detailed GFS documentation is at
  http//www.emc.ncep.noaa.gov/modelinfo/index.html

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• Use the latest ESMF software version, ESMF -
  2.1.1.
• The outputs of the ESMF GFS system is identical
  to the results of the original GFS system.

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Structure of the NCEP ESMF GFS System

• This system uses the ESMF superstructure for its
  top levels. It uses the ESMF Virtual Machine
  (VM), Grid Component, Set Service, Grid,
  DELayout, ESMF interface States and Internal
  State.
• It uses three ESMF Infrastructure utilities,
  Config, Time Manager and Log Error.

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Superstructure of the NCEP ESMF GFS System

• Use ESMF VM with default 1-1 DELayout.
• ESMF internal state contains all necessary
  information to control the model running and to
  restart the run.
• Whole ESMF interface package which contains every
  possible GFS import and export fields as well as
  the diagnostic fields to link different
  applications.

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• Every single ESMF import and export variable
  field has its own switch flag, which can turn on
  or turn off, to flexible link to different
  applications. If just run the stand alone GFS,
  all flags may be turned off to save computational
  cost and storage.

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• Since ESMF has no standard interface state yet
  for the spectral coefficient fields, I use the
  regular FORTRAN array ESMF interface to present
  the spectral coefficient array to create the
  spectral interface state. All ESMF interface
  states are just used for linking out side
  applications. The internal parallel
  decomposition design is not changed to keep its
  original performance.

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• There are four different types of ESMF grid in
  the NCEP ESMF GFS system. They are for the
  single level spectral fields (such as Ps, Zs),
  the multiple level spectral fields(such as wind,
  T, q etc.), the Gaussian grid (such as all
  surface process data) and the date, time
  information. All ESMF interfaces use the default
  1-D DELayout distribution.

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Three ESMF Infrastructure Utilities

• There are three ESMF Infrastructure Utilities in
  the NCEP ESMF GFS system
• ESMF Config
• ESMF Time Manager
• ESMF LogError.

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ESMF Config

• Use a single ESMF config file to input all three
  namelists of the original GFS model.
• Config file also contains all switch flags of the
  ESMF interface states.
• Every single Config parameter read-in is checked
  by the ESMF LogError to make sure all the config
  processes to be successful.

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ESMF Time Manager

• Use the ESMF Time Manager to manage the GFS model
  time related variables.
• Use ESMF Time and ESMF Time Interval variables to
  define the start time, end time, running duration
  length to control the GFS integrating. No
  explicit run do loop appears in the top level
  superstructure routines.

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ESMF LogError

• Use the default ESMF LogError.
• Multiple output files for each processor.
• Log output info set up at every important running
  point to help debug processes.
• Log Error check points are set up when calling
  every ESMF routine and many other subroutines.

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Steps to Create the NCEP ESMF GFS System

• Restructure the original GFS model to create a
  GFS ESMF ready version.
• Develop the ESMF superstructure of the ESMF GFS
  system.
• One by one put in the ESMF infrastructure
  utilities.

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Restructure the Original GFS Model

• The first step to create the ESMF version of GFS
  model is restructuring of the original GFS to
  make it to be a component - subroutine level
  callable.
• Initialize, run and finalize are separated and
  define the internal state which contains all
  necessary information to restart the model run.

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• Move the I/O of the import state out of the Run
  routine, to prepare the ESMF interface states.
• Use a single main drive routine to control the
  model run.
• Use single executable for different resolution
  running. Original GFS needs to re-compile.

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• Removed the common blocks and use module for the
  future run concurrency requirement.

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After Restructuring
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Some ESMF Systems Required to Develop in NCEP

• ESMF version of the NCEP Data Analysis System.
• Create the coupler to link to NCEP data analysis
  system to make the operational cycling run.
• Create the coupler to link the ESMF GFS model
  with GFDL MOM-4 Ocean Model.
• Create the concurrent run version of the NCEP
  ESMF GFS system for NCEP Ensemble operational
  forecasting.

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Final Goal of the ESMF in NCEP

• Make every single model, such as the surface
  process model, ocean model, regional forecast
  model, etc. to be the ESMF version.
• Combine all single NCEP ESMF model to create a
  whole concurrency run package for the NCEP
  operational run purpose.