/[MITgcm]/MITgcm/pkg/zonal_filt/zonal_filter.F
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Revision 1.2 - (hide annotations) (download)
Fri Feb 2 21:36:30 2001 UTC (23 years, 4 months ago) by adcroft
Branch: MAIN
Changes since 1.1: +99 -0 lines
Merged changes from branch "branch-atmos-merge" into MAIN (checkpoint34)
 - substantial modifications to algorithm sequence (dynamics.F)
 - packaged OBCS, Shapiro filter, Zonal filter, Atmospheric Physics

1 adcroft 1.2 C $Header: /u/gcmpack/models/MITgcmUV/pkg/zonal_filt/Attic/zonal_filter.F,v 1.1.2.1 2001/01/24 16:56:07 adcroft Exp $
2    
3     #include "ZONAL_FILT_OPTIONS.h"
4    
5     SUBROUTINE ZONAL_FILTER(
6     U field, fieldMask,
7     I jMin, jMax, kMin, kMax, bi, bj, gridLoc, myThid )
8     C /==========================================================\
9     C | S/R ZONAL_FILTER |
10     C | o Apply FFT filter to a latitude circle. |
11     C \==========================================================/
12     IMPLICIT NONE
13    
14     C == Global data ==
15     #include "SIZE.h"
16     #include "ZONAL_FILT.h"
17     #include "FFTPACK.h"
18    
19     C == Routine arguments ==
20     C jMin - Range of points to filter
21     C jMax
22     C kMin
23     C kMax
24     C bi
25     C bj
26     C myThid - Thread number of this instance of FILTER_LATCIRC_FFT_APPLY
27     C field - Field to filter
28     C gridLoc - Orientation (U or V) of field.
29     INTEGER myThid
30     INTEGER gridLoc
31     Real*8 field(1-OLx:sNx+OLx,1-OLy:sNy+OLy,Nr,nSx,nSy)
32     Real*8 fieldMask(1-Olx:sNx+Olx,1-Oly:sNy+Oly,Nr,nSx,nSy)
33     INTEGER jMin, jMax, kMin, kMax, bi, bj
34    
35     #ifdef ALLOW_ZONAL_FILT
36    
37     C == Local data ==
38     Real*8 phi(Nx)
39     Real*8 phiMask(Nx)
40     Real*8 avPhi
41     INTEGER I, J, K
42    
43     DO k=kMin, kMax
44     DO j=jMin, jMax
45    
46     C o Copy zonal line of field into local workspace
47     DO i=1,sNx
48     phi(I) = field(i,j,k,bi,bj)
49     phiMask(I) = fieldMask(i,j,k,bi,bj)
50     ENDDO
51    
52     C Interpolate through land
53     CALL ZONAL_FILT_PRESMOOTH( phiMask,phi,avPhi,sNx,myThid )
54    
55     C o Forward transform (using specific FFT package)
56     C CALL R8FFTF( Nx, phi, FFTPACKWS(1,bj) )
57     CALL R8FFTF1( Nx, phi,
58     & FFTPACKWS1(1,bj), FFTPACKWS2(1,bj),FFTPACKWS3(1,bj) )
59    
60     C o Apply amplitude filter and normalize
61     IF (gridLoc .EQ. 1) THEN
62     DO i=1, Nx
63     phi(i)=phi(i)*ampFactor(i,j,bi,bj)/float(Nx)
64     ENDDO
65     ELSEIF (gridLoc .EQ. 2) THEN
66     DO i=1, Nx
67     phi(i)=phi(i)*ampFactorV(i,j,bi,bj)/float(Nx)
68     ENDDO
69     ELSE
70     WRITE(0,*) 'Error: gridLoc = ',gridLoc
71     STOP 'Error: gridLoc has illegal value'
72     ENDIF
73    
74     C o Backward transform (using specific FFT package)
75     C CALL R8FFTB( Nx, phi, FFTPACKWS(1,bj) )
76     CALL R8FFTB1( Nx, phi,
77     & FFTPACKWS1(1,bj), FFTPACKWS2(1,bj),FFTPACKWS3(1,bj) )
78    
79     C De-interpolate through land
80     CALL ZONAL_FILT_POSTSMOOTH(phiMask,phi,avPhi,sNx,myThid)
81    
82     C o Do periodic wrap around by hand
83     DO i=1-OLx,0
84     field(i,j,k,bi,bj) = phi(sNx+i)
85     ENDDO
86     DO i=1,sNx
87     field(i,j,k,bi,bj) = phi(I)
88     ENDDO
89     DO i=sNx+1,sNx+OLx
90     field(i,j,k,bi,bj) = phi(i-sNx)
91     ENDDO
92    
93     ENDDO
94     ENDDO
95    
96     #endif /* ALLOW_ZONAL_FILT */
97    
98     RETURN
99     END

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