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Subsections


3.9.3 Code Configuration

The model configuration for this experiment resides under the directory verification/tutorial_barotropic_gyre/. The experiment files

  • input/data
  • input/data.pkg
  • input/eedata,
  • input/windx.sin_y,
  • input/topog.box,
  • code/CPP_EEOPTIONS.h
  • code/CPP_OPTIONS.h,
  • code/SIZE.h.
contain the code customizations and parameter settings for this experiments. Below we describe the customizations to these files associated with this experiment.

3.9.3.1 File input/data

This file, reproduced completely below, specifies the main parameters for the experiment. The parameters that are significant for this configuration are

  • Line 7, 
     viscAh=4.E2,
    this line sets the Laplacian friction coefficient to $ 400 m^2s^{-1}$
  • Line 10, 
     beta=1.E-11,
    this line sets $ \beta$ (the gradient of the coriolis parameter, $ f$ ) to $ 10^{-11} s^{-1}m^{-1}$

  • Lines 15 and 16 
    rigidLid=.FALSE.,
implicitFreeSurface=.TRUE.,
    these lines suppress the rigid lid formulation of the surface pressure inverter and activate the implicit free surface form of the pressure inverter.

  • Line 27, 
    startTime=0,
    this line indicates that the experiment should start from $ t=0$ and implicitly suppresses searching for checkpoint files associated with restarting an numerical integration from a previously saved state.

  • Line 29, 
    endTime=12000,
    this line indicates that the experiment should start finish at $ t=12000s$ . A restart file will be written at this time that will enable the simulation to be continued from this point.

  • Line 30, 
    deltaTmom=1200,
    This line sets the momentum equation timestep to $ 1200s$ .

  • Line 39, 
    usingCartesianGrid=.TRUE.,
    This line requests that the simulation be performed in a Cartesian coordinate system.

  • Line 41, 
    delX=60*20E3,
    This line sets the horizontal grid spacing between each x-coordinate line in the discrete grid. The syntax indicates that the discrete grid should be comprise of $ 60$ grid lines each separated by $ 20 \times 10^{3}m$ ($ 20$  km).

  • Line 42, 
    delY=60*20E3,
    This line sets the horizontal grid spacing between each y-coordinate line in the discrete grid to $ 20 \times 10^{3}m$ ($ 20$  km).

  • Line 43, 
    delZ=5000,
    This line sets the vertical grid spacing between each z-coordinate line in the discrete grid to $ 5000m$ ($ 5$  km).

  • Line 46, 
    bathyFile='topog.box'
    This line specifies the name of the file from which the domain bathymetry is read. This file is a two-dimensional ($ x,y$ ) map of depths. This file is assumed to contain 64-bit binary numbers giving the depth of the model at each grid cell, ordered with the x coordinate varying fastest. The points are ordered from low coordinate to high coordinate for both axes. The units and orientation of the depths in this file are the same as used in the MITgcm code. In this experiment, a depth of $ 0m$ indicates a solid wall and a depth of $ -5000m$ indicates open ocean. The matlab program input/gendata.m shows an example of how to generate a bathymetry file.

  • Line 49, 
    zonalWindFile='windx.sin_y'
    This line specifies the name of the file from which the x-direction surface wind stress is read. This file is also a two-dimensional ($ x,y$ ) map and is enumerated and formatted in the same manner as the bathymetry file. The matlab program input/gendata.m includes example code to generate a valid zonalWindFile file.

other lines in the file input/data are standard values that are described in the MITgcm Getting Started and MITgcm Parameters notes. 

# Model parameters
# Continuous equation parameters
 &PARM01
 tRef=20.,
 sRef=10.,
 viscAz=1.E-2,
 viscAh=4.E2,
 diffKhT=4.E2,
 diffKzT=1.E-2,
 beta=1.E-11,
 tAlpha=2.E-4,
 sBeta =0.,
 gravity=9.81,
 gBaro=9.81,
 rigidLid=.FALSE.,
 implicitFreeSurface=.TRUE.,
 eosType='LINEAR',
 readBinaryPrec=64,
 &
# Elliptic solver parameters
 &PARM02
 cg2dMaxIters=1000,
 cg2dTargetResidual=1.E-7,
 &
# Time stepping parameters
 &PARM03
 startTime=0,
#endTime=311040000,
 endTime=12000.0,
 deltaTmom=1200.0,
 deltaTtracer=1200.0,
 abEps=0.1,
 pChkptFreq=2592000.0,
 chkptFreq=120000.0,
 dumpFreq=2592000.0,
 &
# Gridding parameters
 &PARM04
 usingCartesianGrid=.TRUE.,
 usingSphericalPolarGrid=.FALSE.,
 delX=60*20E3,
 delY=60*20E3,
 delZ=5000.,
 &
 &PARM05
 bathyFile='topog.box',
 hydrogThetaFile=,
 hydrogSaltFile=,
 zonalWindFile='windx.sin_y',
 meridWindFile=,
 &

3.9.3.2 File input/data.pkg

This file uses standard default values and does not contain customizations for this experiment.

3.9.3.3 File input/eedata

This file uses standard default values and does not contain customizations for this experiment.

3.9.3.4 File input/windx.sin_y

The input/windx.sin_y file specifies a two-dimensional ($ x,y$ ) map of wind stress ,$ \tau_{x}$ , values. The units used are $ Nm^{-2}$ . Although $ \tau_{x}$ is only a function of $ y$ n in this experiment this file must still define a complete two-dimensional map in order to be compatible with the standard code for loading forcing fields in MITgcm. The included matlab program input/gendata.m gives a complete code for creating the input/windx.sin_y file.

3.9.3.5 File input/topog.box

The input/topog.box file specifies a two-dimensional ($ x,y$ ) map of depth values. For this experiment values are either $ 0m$ or -delZm, corresponding respectively to a wall or to deep ocean. The file contains a raw binary stream of data that is enumerated in the same way as standard MITgcm two-dimensional, horizontal arrays. The included matlab program input/gendata.m gives a complete code for creating the input/topog.box file.

3.9.3.6 File code/SIZE.h

Two lines are customized in this file for the current experiment

  • Line 39, 
     sNx=60,
    this line sets the lateral domain extent in grid points for the axis aligned with the x-coordinate.

  • Line 40, 
     sNy=60,
    this line sets the lateral domain extent in grid points for the axis aligned with the y-coordinate. 

C $Header: /u/gcmpack/manual/s_examples/barotropic_gyre/code/SIZE.h,v 1.2 2001/09/27 00:58:17 cnh Exp $
C $Name:  $
C
C     /==========================================================\
C     | SIZE.h Declare size of underlying computational grid.    |
C     |==========================================================|
C     | The design here support a three-dimensional model grid   |
C     | with indices I,J and K. The three-dimensional domain     |
C     | is comprised of nPx*nSx blocks of size sNx along one axis|
C     | nPy*nSy blocks of size sNy along another axis and one    |
C     | block of size Nz along the final axis.                   |
C     | Blocks have overlap regions of size OLx and OLy along the|
C     | dimensions that are subdivided.                          |
C     \==========================================================/
C     Voodoo numbers controlling data layout.
C     sNx - No. X points in sub-grid.
C     sNy - No. Y points in sub-grid.
C     OLx - Overlap extent in X.
C     OLy - Overlat extent in Y.
C     nSx - No. sub-grids in X.
C     nSy - No. sub-grids in Y.
C     nPx - No. of processes to use in X.
C     nPy - No. of processes to use in Y.
C     Nx  - No. points in X for the total domain.
C     Ny  - No. points in Y for the total domain.
C     Nr  - No. points in R for full process domain.
      INTEGER sNx
      INTEGER sNy
      INTEGER OLx
      INTEGER OLy
      INTEGER nSx
      INTEGER nSy
      INTEGER nPx
      INTEGER nPy
      INTEGER Nx
      INTEGER Ny
      INTEGER Nr
      PARAMETER (
     &           sNx =  60,
     &           sNy =  60,
     &           OLx =   3,
     &           OLy =   3,
     &           nSx =   1,
     &           nSy =   1,
     &           nPx =   1,
     &           nPy =   1,
     &           Nx  = sNx*nSx*nPx,
     &           Ny  = sNy*nSy*nPy,
     &           Nr  =   1)

C     MAX_OLX  - Set to the maximum overlap region size of any array
C     MAX_OLY    that will be exchanged. Controls the sizing of exch
C                routine buufers.
      INTEGER MAX_OLX
      INTEGER MAX_OLY
      PARAMETER ( MAX_OLX = OLx,
     &            MAX_OLY = OLy )

3.9.3.7 File code/CPP_OPTIONS.h

This file uses standard default values and does not contain customizations for this experiment.

3.9.3.8 File code/CPP_EEOPTIONS.h

This file uses standard default values and does not contain customizations for this experiment.

next up previous contents
Next: 3.10 Baroclinic Gyre MITgcm Up: 3.9 Barotropic Gyre MITgcm Previous: 3.9.2 Discrete Numerical Configuration   Contents
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