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Next: 3.13.6 Running the example Up: 3.13 Surface Driven Convection Previous: 3.13.4 Numerical stability criteria   Contents

Subsections


3.13.5 Experiment configuration

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

  • code/CPP_EEOPTIONS.h
  • code/CPP_OPTIONS.h,
  • code/SIZE.h.
  • input/data
  • input/data.pkg
  • input/eedata,
  • input/Qsurf.bin,
contain the code customisations and parameter settings for this experiment. Below we describe these experiment-specific customisations.


3.13.5.1 File code/CPP_EEOPTIONS.h

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


3.13.5.2 File code/CPP_OPTIONS.h

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


3.13.5.3 File code/SIZE.h

Three lines are customized in this file. These prescribe the domain grid dimensions.

  • Line 36, 
     sNx=64,
    this line sets the lateral domain extent in grid points for the axis aligned with the $ x$-coordinate.

  • Line 37, 
     sNy=64,
    this line sets the lateral domain extent in grid points for the axis aligned with the $ y$-coordinate.

  • Line 46, 
     Nr=20,
    this line sets the vertical domain extent in grid points. 

C 
$ Header: /u/gcmpack/manual/part3/case_studies/doubly_periodic_convection/code/SIZE.h,v 1.1 2001/12/19 14:34:39 helen 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 Z 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 =  64,
     &           sNy =  64,
     &           OLx =   3,
     &           OLy =   3,
     &           nSx =   1,
     &           nSy =   1,
     &           nPx =   1,
     &           nPy =   1,
     &           Nx  = sNx*nSx*nPx,
     &           Ny  = sNy*nSy*nPy,
     &           Nr  =  20)



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 )


3.13.5.4 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 4, 
         4   tRef=20*20.0,
    this line sets the initial and reference values of potential temperature at each model level in units of $ ^{\circ }$C. Here the value is arbitrary since, in this case, the flow evolves independently of the absolute magnitude of the reference temperature. For each depth level the initial and reference profiles will be uniform in $ x$ and $ y$. The values specified are read into the variable tRef in the model code, by procedure S/R INI_PARMS (ini_parms.F) . The temperature field is initialised, by procedure S/R INI_THETA (ini_theta.F) .

  • Line 5, 
         5   sRef=20*35.0,
    this line sets the initial and reference values of salinity at each model level in units of ppt. In this case salinity is set to an (arbitrary) uniform value of 35.0 ppt. However since, in this example, density is independent of salinity, an appropriatly defined initial salinity could provide a useful passive tracer. For each depth level the initial and reference profiles will be uniform in $ x$ and $ y$. The values specified are read into the variable sRef in the model code, by procedure S/R INI_PARMS (ini_parms.F) . The salinity field is initialised, by procedure S/R INI_SALT (ini_salt.F) .

  • Line 6, 
         6   viscAh=0.1,
    this line sets the horizontal laplacian dissipation coefficient to 0.1 $ {\rm m^{2}s^{-1}}$. Boundary conditions for this operator are specified later. The variable viscAh is read in the routine S/R INI_PARMS (ini_params.F) and applied in routines S/R CALC_MOM_RHS (calc_mom_rhs.F) and S/R CALC_GW (calc_gw.F) .

  • Line 7, 
         7   viscAz=0.1,
    this line sets the vertical laplacian frictional dissipation coefficient to 0.1 $ {\rm m^{2}s^{-1}}$. Boundary conditions for this operator are specified later. The variable viscAz is read in the routine S/R INI_PARMS (ini_parms.F) and is copied into model general vertical coordinate variable viscAr . At each time step, the viscous term contribution to the momentum equations is calculated in routine S/R CALC_DIFFUSIVITY (calc_diffusivity.F) .

  • Line 8, 
    no_slip_sides=.FALSE.
    this line selects a free-slip lateral boundary condition for the horizontal laplacian friction operator e.g. $ \frac{\partial u}{\partial y}$=0 along boundaries in $ y$ and $ \frac{\partial v}{\partial x}$=0 along boundaries in $ x$. The variable no_slip_sides is read in the routine S/R INI_PARMS (ini_parms.F) and the boundary condition is evaluated in routine S/R CALC_MOM_RHS (calc_mom_rhs.F) .

  • Lines 9, 
    no_slip_bottom=.TRUE.
    this line selects a no-slip boundary condition for the bottom boundary condition in the vertical laplacian friction operator e.g. $ u=v=0$ at $ z=-H$, where $ H$ is the local depth of the domain. The variable no_slip_bottom is read in the routine S/R INI_PARMS (ini_parms.F) and is applied in the routine S/R CALC_MOM_RHS (calc_mom_rhs.F) .

  • Line 11, 
    diffKhT=0.1,
    this line sets the horizontal diffusion coefficient for temperature to 0.1 $ \rm m^{2}s^{-1}$. The boundary condition on this operator is $ \frac{\partial}{\partial x}=\frac{\partial}{\partial y}=0$ at all boundaries. The variable diffKhT is read in the routine S/R INI_PARMS (ini_parms.F) and used in routine S/R CALC_GT (calc_gt.F) .

  • Line 12, 
    diffKzT=0.1,
    this line sets the vertical diffusion coefficient for temperature to 0.1 $ {\rm m^{2}s^{-1}}$. The boundary condition on this operator is $ \frac{\partial}{\partial z}$ = 0 on all boundaries. The variable diffKzT is read in the routine S/R INI_PARMS (ini_parms.F) . It is copied into model general vertical coordinate variable diffKrT which is used in routine S/R CALC_DIFFUSIVITY (calc_diffusivity.F) .

  • Line 13, 
    diffKhS=0.1,
    this line sets the horizontal diffusion coefficient for salinity to 0.1 $ \rm m^{2}s^{-1}$. The boundary condition on this operator is $ \frac{\partial}{\partial x}=\frac{\partial}{\partial y}=0$ on all boundaries. The variable diffKsT is read in the routine S/R INI_PARMS (ini_parms.F) and used in routine S/R CALC_GS (calc_gs.F) .

  • Line 14, 
    diffKzS=0.1,
    this line sets the vertical diffusion coefficient for temperature to 0.1 $ {\rm m^{2}s^{-1}}$. The boundary condition on this operator is $ \frac{\partial}{\partial z}$ = 0 on all boundaries. The variable diffKzS is read in the routine S/R INI_PARMS (ini_parms.F) . It is copied into model general vertical coordinate variable diffKrS which is used in routine S/R CALC_DIFFUSIVITY (calc_diffusivity.F) .

  • Line 15, 
    f0=1E-4,
    this line sets the Coriolis parameter to $ 1 \times 10^{-4}$ s$ ^{-1}$. Since $ \beta = 0.0$ this value is then adopted throughout the domain.

  • Line 16, 
    beta=0.E-11,
    this line sets the the variation of Coriolis parameter with latitude to 0.

  • Line 17, 
    tAlpha=2.E-4,
    This line sets the thermal expansion coefficient for the fluid to $ 2 \times 10^{-4}$ $ ^o$ C$ ^{-1}$. The variable tAlpha is read in the routine S/R INI_PARMS (ini_parms.F) . The routine S/R FIND_RHO (find_rho.F) makes use of tAlpha.

  • Line 18, 
    sBeta=0,
    This line sets the saline expansion coefficient for the fluid to 0 consistent with salt's passive role in this example.

  • Line 23-24, 
    rigidLid=.FALSE., 
implicitFreeSurface=.TRUE.,
    Selects the barotropic pressure equation to be the implicit free surface formulation.

  • Line 25, 
    eosType='LINEAR',
    Selects the linear form of the equation of state.

  • Line 26, 
    nonHydrostatic=.TRUE.,
    Selects for non-hydrostatic code.

  • Line 27, 
    readBinaryPrec=64,
    Sets format for reading binary input datasets holding model fields to use 64-bit representation for floating-point numbers.

  • Line 31, 
    cg2dMaxIters=1000,
    Inactive - the pressure field in a non-hydrostatic simulation is inverted through a 3D elliptic equation.

  • Line 32, 
    cg2dTargetResidual=1.E-9,
    Inactive - the pressure field in a non-hydrostatic simulation is inverted through a 3D elliptic equation.

  • Line 33, 
    cg3dMaxIters=40,
    This line sets the maximum number of iterations the three-dimensional, conjugate gradient solver will use to 40, irrespective of the convergence criteria being met. Used in routine S/R CG3D (cg3d.F) .

  • Line 34, 
    cg3dTargetResidual=1.E-9,
    Sets the tolerance which the three-dimensional, conjugate gradient solver will use to test for convergence in equation [*] to $ 1 \times 10^{-9}$. The solver will iterate until the tolerance falls below this value or until the maximum number of solver iterations is reached. Used in routine S/R CG3D (cg3d.F) .

  • Line 38, 
    startTime=0,
    Sets the starting time for the model internal time counter. When set to non-zero this option implicitly requests a checkpoint file be read for initial state. By default the checkpoint file is named according to the integer number of time steps in the startTime value. The internal time counter works in seconds.

  • Line 39, 
    nTimeSteps=8640.,
    Sets the number of timesteps at which this simulation will terminate (in this case 8640 timesteps or 1 day or $ \delta t = 10$ s). At the end of a simulation a checkpoint file is automatically written so that a numerical experiment can consist of multiple stages.

  • Line 40, 
    deltaT=10,
    Sets the timestep $ \delta t$ to 10 s.

  • Line 51, 
    dXspacing=50.0,
    Sets horizontal ($ x$-direction) grid interval to 50 m.

  • Line 52, 
    dYspacing=50.0,
    Sets horizontal ($ y$-direction) grid interval to 50 m.

  • Line 53, 
    delZ=20*50.0,
    Sets vertical grid spacing to 50 m. Must be consistent with code/SIZE.h. Here, 20 corresponds to the number of vertical levels.

  • Line 57, 
    surfQfile='Qsurf.bin'
    This line specifies the name of the file from which the surface heat flux is read. This file is a two-dimensional ($ x,y$) map. It is assumed to contain 64-bit binary numbers giving the value of $ Q$ (W m$ ^2$) to be applied in each surface grid cell, ordered with the $ x$ coordinate varying fastest. The points are ordered from low coordinate to high coordinate for both axes. The matlab program input/gendata.m shows how to generate the surface heat flux file used in the example. The variable Qsurf is read in the routine S/R INI_PARMS (ini_parms.F) and applied in S/R EXTERNAL_FORCING_SURF (external_forcing_surf.F) where the flux is converted to a temperature tendency. 

# ====================
# | Model parameters |
# ====================
#
# Continuous equation parameters
 &PARM01
 tRef=20*20.0,
 sRef=20*35.0,
 viscAh=0.1,
 viscAz=0.1,
 no_slip_sides=.FALSE.,
 no_slip_bottom=.FALSE.,
 viscA4=0.E12,
 diffKhT=0.1,
 diffKzT=0.1,
 diffKhS=0.1,
 diffKzS=0.1,
 f0=1E-4,
 beta=0.E-11,
 tAlpha=2.0E-4,
 sBeta =0.,
 gravity=9.81,
 rhoConst=1000.0,
 rhoNil=1000.0,
 heatCapacity_Cp=3900.0,
 rigidLid=.FALSE.,
 implicitFreeSurface=.TRUE.,
 eosType='LINEAR',
 nonHydrostatic=.TRUE.,
 readBinaryPrec=64,
 &



# Elliptic solver parameters
 &PARM02
 cg2dMaxIters=1000,
 cg2dTargetResidual=1.E-9,
 cg3dMaxIters=40,
 cg3dTargetResidual=1.E-9,
 &



# Time stepping parameters
 &PARM03
 nIter0=0,
 nTimeSteps=1440,
 deltaT=60,
 abEps=0.1,
 pChkptFreq=0.0,
 chkptFreq=0.0,
 dumpFreq=600,
 monitorFreq=1.E-5,
 &



# Gridding parameters
 &PARM04
 usingCartesianGrid=.TRUE.,
 usingSphericalPolarGrid=.FALSE.,
 dXspacing=50.0,
 dYspacing=50.0,
 delZ=20*50.0,
 &



# Input datasets
 &PARM05
 surfQfile='Qnet.circle',
 &


3.13.5.5 File input/data.pkg

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


3.13.5.6 File input/eedata

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


3.13.5.7 File input/Qsurf.bin

The file input/Qsurf.bin specifies a two-dimensional ($ x,y$) map of heat flux values where $ Q = Q_o \times ( 0.5 +$   random number between 0 and 1$ )$.

In the example $ Q_o = 800$ W m$ ^{-2}$ so that values of $ Q$ lie in the range 400 to 1200 W m$ ^{-2}$ with a mean of $ Q_o$. Although the flux models a loss, because it is directed upwards, according to the model's sign convention, $ Q$ is positive.

Figure 3.13:

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Next: 3.13.6 Running the example Up: 3.13 Surface Driven Convection Previous: 3.13.4 Numerical stability criteria   Contents
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