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C $Header: /u/gcmpack/MITgcm/pkg/zonal_filt/zonal_filt_init.F,v 1.6 2010/01/31 20:24:16 jmc Exp $ |
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C $Name: $ |
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|
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#include "ZONAL_FILT_OPTIONS.h" |
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|
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CBOP |
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C !ROUTINE: ZONAL_FILT_INIT |
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C !INTERFACE: |
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SUBROUTINE ZONAL_FILT_INIT( myThid ) |
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|
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C !DESCRIPTION: \bv |
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C *==========================================================* |
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C | S/R ZONAL_FILT_INIT |
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C | o Initialise FFT filter for latitude circle. |
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C *==========================================================* |
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C | The details of particular FFT libraries may differ. |
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C | Changing to a different library may entail modifying the |
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C | code here. However, the broad process is usually the |
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C | same. |
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C | Note - Fourier modes for sNx and sNx+1 are damped in the |
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C | same way. This is because we have not implemented |
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C | a scheme that sets the damping factor for the |
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C | highest wave number for odd sNx. Instead the |
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C | highest wave number for odd sNx. Instead only |
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C | wave numbers 1:INT(sNx/2) are partially damped. |
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C | Wave number sNx/2 (if it exists) is removed |
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C | altogether. |
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C *==========================================================* |
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C \ev |
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|
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C !USES: |
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IMPLICIT NONE |
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|
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C === Global variables === |
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#include "SIZE.h" |
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#include "EEPARAMS.h" |
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#include "PARAMS.h" |
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#include "GRID.h" |
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#include "ZONAL_FILT.h" |
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#include "FFTPACK.h" |
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|
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C !INPUT/OUTPUT PARAMETERS: |
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C == Routine arguments == |
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C myThid :: my Thread Id number |
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INTEGER myThid |
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CEOP |
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|
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#ifdef ALLOW_ZONAL_FILT |
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C !LOCAL VARIABLES: |
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C == Local variables == |
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C alpha :: Used to evaluate frequency and latitude dependent |
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C amplitude damping factor. |
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C wvNum :: Wave number |
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C lat :: Temporary holding latitude |
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C nWv :: No. of waves that fit on grid. |
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C msgBuf :: Informational/error message buffer |
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c _RL alpha, wvNum |
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c INTEGER nWv |
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INTEGER i, j, bi, bj |
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CHARACTER*(MAX_LEN_MBUF) msgBuf |
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|
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C !FUNCTIONS: |
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_RL oneRL |
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_RL ampfact |
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PARAMETER( oneRL = 1. _d 0 ) |
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_RS lat |
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ampfact(lat,i) = MIN( oneRL, |
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& ( COS( ABS(lat)*deg2rad ) |
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& /COS( zonal_filt_lat*deg2rad ) )**zonal_filt_cospow |
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& /(SIN( PI*FLOAT(i)/FLOAT(Nx) ) )**zonal_filt_sinpow |
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& ) |
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|
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C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----| |
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|
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IF ( sNx.NE.Nx ) THEN |
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WRITE(msgBuf,'(A,I3,A)') |
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& 'S/R ZONAL_FILT_INIT: Multi-tiles ( nSx*nPx=', nSx*nPx, ' )' |
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CALL PRINT_ERROR( msgBuf, myThid ) |
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WRITE(msgBuf,'(A)') |
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& ' in Zonal (X) dir. not implemented in Zonal-Filter code' |
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CALL PRINT_ERROR( msgBuf, myThid ) |
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STOP 'ABNORMAL END: S/R ZONAL_FILT_INIT' |
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ENDIF |
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|
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_BEGIN_MASTER(myThid) |
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C o Initialise specific library FFT package |
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DO bj=1,nSy |
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c CALL R8FFTI( Nx, FFTPACKWS(1,bj) ) |
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CALL R8FFTI1( Nx, FFTPACKWS2(1,bj), FFTPACKWS3(1,bj) ) |
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ENDDO |
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|
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C o Set amplitude scale factor as function of latitude and mode number |
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DO bj=1,nSy |
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DO bi=1,nSx |
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DO j=1-oLy,sNy+Oly |
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ampFactor(1,j,bi,bj) = oneRL |
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ampFactorV(1,j,bi,bj) = oneRL |
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DO i=1,Nx/2-1 |
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ampFactor(2*i,j,bi,bj) = ampfact( yC(1,j,bi,bj) , I ) |
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c IF (ampFactor(2*i,j,bi,bj).LE..9) ampFactor(2*i,j,bi,bj)=0. |
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ampFactor(2*I+1,j,bi,bj) = ampFactor(2*i,j,bi,bj) |
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ampFactorV(2*i,j,bi,bj) = ampfact( yG(1,j,bi,bj) , I ) |
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c IF (ampFactorV(2*i,j,bi,bj).LE..9) ampFactorV(2*i,j,bi,bj)=0. |
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ampFactorV(2*I+1,j,bi,bj) = ampFactorV(2*i,j,bi,bj) |
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ENDDO |
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|
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i=Nx/2 |
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IF ( zonal_filt_mode2dx.EQ.0 ) THEN |
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ampFactor(Nx,j,bi,bj) = ampfact( yC(1,j,bi,bj) , i ) |
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ampFactorV(Nx,j,bi,bj) = ampfact( yG(1,j,bi,bj) , i ) |
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ELSE |
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ampFactor(Nx,j,bi,bj) = 0. |
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ampFactorV(Nx,j,bi,bj) = 0. |
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ENDIF |
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|
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ENDDO |
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ENDDO |
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ENDDO |
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_END_MASTER(myThid) |
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CALL BAR2(myThid) |
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|
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CALL WRITE_REC_XY_RL( 'ampFactor', ampFactor, 1, 0, myThid ) |
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|
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#endif /* ALLOW_ZONAL_FILT */ |
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|
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RETURN |
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END |
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