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C $Header: /u/gcmpack/MITgcm/pkg/exf/exf_interp.F,v 1.20 2007/05/10 22:21:08 jmc Exp $ |
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C $Name: $ |
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|
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#include "EXF_OPTIONS.h" |
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|
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CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC |
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C Flux Coupler using C |
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C Bilinear interpolation of forcing fields C |
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C C |
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C B. Cheng (12/2002) C |
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C C |
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C added Bicubic (bnc 1/2003) C |
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C C |
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CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC |
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|
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_RL FUNCTION LAGRAN(i,x,a,sp) |
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|
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INTEGER i |
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_RS x |
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_RL a(4) |
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INTEGER sp |
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|
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C- local variables: |
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INTEGER k |
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_RL numer,denom |
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|
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numer = 1. _d 0 |
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denom = 1. _d 0 |
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|
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do k=1,sp |
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if ( k .ne. i) then |
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denom = denom*(a(i) - a(k)) |
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numer = numer*(x - a(k)) |
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endif |
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enddo |
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|
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lagran = numer/denom |
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|
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RETURN |
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END |
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|
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|
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SUBROUTINE exf_interp( |
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I infile, |
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I filePrec, |
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O arrayout, |
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I irecord, xG_in, yG, |
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I lon_0, lon_inc, |
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I lat_0, lat_inc, |
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I nx_in, ny_in, method, mythid) |
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|
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implicit none |
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|
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C infile (string) :: name of the binary input file (direct access) |
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C filePrec (integer) :: number of bits per word in file (32 or 64) |
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C arrout ( _RL ) :: output array |
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C irecord (integer) :: record number to read |
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C xG,yG :: coordinates for output grid to interpolate to |
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C lon_0, lat_0 :: lon and lat of sw corner of global input grid |
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C lon_inc :: scalar x-grid increment |
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C lat_inc :: vector y-grid increments |
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C nx_in,ny_in (integer) :: size in x & y direction of input file to read |
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C method :: 1,11,21 for bilinear; 2,12,22 for bicubic |
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C :: 1,2 for tracer; 11,12 for U; 21,22 for V |
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C myThid (integer) :: My Thread Id number |
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C |
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|
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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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|
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C subroutine variables |
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character*(*) infile |
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integer filePrec, irecord, nx_in, ny_in |
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_RL arrayout(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy) |
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_RS xG_in (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy) |
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_RS yG (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy) |
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_RL lon_0, lon_inc |
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_RL lat_0, lat_inc(ny_in-1) |
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integer method, mythid |
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|
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C functions |
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external lagran |
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_RL lagran |
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|
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C local variables |
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integer e_ind(snx,sny),w_ind(snx,sny) |
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integer n_ind(snx,sny),s_ind(snx,sny) |
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_RL px_ind(4), py_ind(4), ew_val(4) |
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_RL arrayin(-1:nx_in+2 , -1:ny_in+2) |
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_RL NorthValue |
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_RL x_in (-1:nx_in+2), y_in(-1:ny_in+2) |
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integer i, j, k, l, js, bi, bj, sp, interp_unit |
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_RS xG(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy) |
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_RL ninety |
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PARAMETER ( ninety = 90. ) |
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_RS threeSixtyRS |
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PARAMETER ( threeSixtyRS = 360. ) |
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|
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C put xG in interval [ lon_0 , lon_0+360 [ |
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do bj=myByLo(myThid),myByHi(myThid) |
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do bi=myBxLo(myThid),myBxHi(myThid) |
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do j=1-OLy,sNy+OLy |
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do i=1-OLx,sNx+OLx |
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xG(i,j,bi,bj) = xG_in(i,j,bi,bj)-lon_0 |
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& + threeSixtyRS*2. |
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xG(i,j,bi,bj) = lon_0+mod(xG(i,j,bi,bj),threeSixtyRS) |
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enddo |
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enddo |
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enddo |
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enddo |
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|
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call exf_interp_read( |
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I infile, filePrec, |
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O arrayin, |
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I irecord, nx_in, ny_in, mythid) |
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|
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C setup input longitude grid |
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do i=-1,nx_in+2 |
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x_in(i) = lon_0 + (i-1)*lon_inc |
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enddo |
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|
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C setup input latitude grid |
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y_in(0) = lat_0 - lat_inc(1) |
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y_in(-1)= lat_0 - 2.*lat_inc(1) |
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y_in(1) = lat_0 |
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do j=2,ny_in |
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y_in(j) = y_in(j-1) + lat_inc(j-1) |
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enddo |
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do j=ny_in+1,ny_in+2 |
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if (y_in(j-1).eq.ninety) then |
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y_in(j) = 2 * ninety - y_in(j-2) |
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else |
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y_in(j) = min( y_in(j-1)+lat_inc(ny_in-1), ninety ) |
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endif |
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enddo |
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|
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C enlarge boundary |
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do j=1,ny_in |
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arrayin(0,j) = arrayin(nx_in,j) |
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arrayin(-1,j) = arrayin(nx_in-1,j) |
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arrayin(nx_in+1,j) = arrayin(1,j) |
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arrayin(nx_in+2,j) = arrayin(2,j) |
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enddo |
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do i=-1,nx_in+2 |
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arrayin(i,0) = arrayin(i,1) |
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arrayin(i,-1) = arrayin(i,1) |
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arrayin(i,ny_in+1) = arrayin(i,ny_in) |
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arrayin(i,ny_in+2) = arrayin(i,ny_in) |
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enddo |
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|
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C For tracer (method=1,2) set to northernmost zonal-mean value |
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C at 90N to avoid sharp zonal gradients near the Pole. |
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C For U (method=11,12) set to zero at 90N to minimize velocity |
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C gradient at North Pole |
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C For V (method=11,12) set to northernmost zonal value at 90N, |
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C as is already done above in order to allow cross-PoleArctic flow |
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do j=ny_in,ny_in+2 |
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if (y_in(j).eq.ninety) then |
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if (method.eq.1 .or. method.eq.2) then |
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NorthValue = 0. |
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do i=1,nx_in |
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NorthValue = NorthValue + arrayin(i,j) |
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enddo |
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NorthValue = NorthValue / nx_in |
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do i=-1,nx_in+2 |
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arrayin(i,j) = NorthValue |
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enddo |
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elseif (method.eq.11 .or. method.eq.12) then |
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do i=-1,nx_in+2 |
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arrayin(i,j) = 0. |
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enddo |
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endif |
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endif |
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enddo |
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|
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do bj = mybylo(mythid), mybyhi(mythid) |
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do bi = mybxlo(mythid), mybxhi(mythid) |
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|
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C check validity of input/output coordinates |
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#ifdef ALLOW_DEBUG |
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if ( debugLevel .ge. debLevB ) then |
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do i=1,snx |
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do j=1,sny |
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if ( xG(i,j,bi,bj) .lt. x_in(0) .or. |
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& xG(i,j,bi,bj) .ge. x_in(nx_in+1) .or. |
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& yG(i,j,bi,bj) .lt. y_in(0) .or. |
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& yG(i,j,bi,bj) .ge. y_in(ny_in+1) ) then |
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print*,'ERROR in S/R EXF_INTERP:' |
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print*,' input grid must encompass output grid.' |
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print*,'i,j,bi,bj' ,i,j,bi,bj |
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print*,'xG,yG' ,xG(i,j,bi,bj),yG(i,j,bi,bj) |
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print*,'nx_in,ny_in' ,nx_in ,ny_in |
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print*,'x_in(0,nx_in+1)',x_in(0) ,x_in(nx_in+1) |
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print*,'y_in(0,ny_in+1)',y_in(0) ,y_in(ny_in+1) |
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STOP ' ABNORMAL END: S/R EXF_INTERP' |
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endif |
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enddo |
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enddo |
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endif |
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#endif /* ALLOW_DEBUG */ |
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|
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C compute interpolation indices |
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do i=1,snx |
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do j=1,sny |
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if (xG(i,j,bi,bj)-x_in(1) .ge. 0.) then |
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w_ind(i,j) = int((xG(i,j,bi,bj)-x_in(1))/lon_inc) + 1 |
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else |
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w_ind(i,j) = int((xG(i,j,bi,bj)-x_in(1))/lon_inc) |
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endif |
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e_ind(i,j) = w_ind(i,j) + 1 |
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js = ny_in*.5 |
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do while (yG(i,j,bi,bj) .lt. y_in(js)) |
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js = (js - 1)*.5 |
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enddo |
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do while (yG(i,j,bi,bj) .ge. y_in(js+1)) |
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js = js + 1 |
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enddo |
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s_ind(i,j) = js |
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n_ind(i,j) = js + 1 |
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enddo |
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enddo |
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|
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if (method.eq.1 .or. method.eq.11 .or. method.eq.21) then |
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|
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C bilinear interpolation |
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sp = 2 |
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do j=1,sny |
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do i=1,snx |
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arrayout(i,j,bi,bj) = 0. |
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do l=0,1 |
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px_ind(l+1) = x_in(w_ind(i,j)+l) |
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py_ind(l+1) = y_in(s_ind(i,j)+l) |
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enddo |
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do k=1,2 |
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ew_val(k) = arrayin(w_ind(i,j),s_ind(i,j)+k-1) |
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& *lagran(1,xG(i,j,bi,bj),px_ind,sp) |
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& +arrayin(e_ind(i,j),s_ind(i,j)+k-1) |
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& *lagran(2,xG(i,j,bi,bj),px_ind,sp) |
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arrayout(i,j,bi,bj)=arrayout(i,j,bi,bj) |
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& +ew_val(k)*lagran(k,yG(i,j,bi,bj),py_ind,sp) |
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enddo |
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enddo |
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enddo |
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elseif (method .eq. 2 .or. method.eq.12 .or. method.eq.22) then |
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|
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C bicubic interpolation |
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sp = 4 |
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do j=1,sny |
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do i=1,snx |
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arrayout(i,j,bi,bj) = 0. |
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do l=-1,2 |
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px_ind(l+2) = x_in(w_ind(i,j)+l) |
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py_ind(l+2) = y_in(s_ind(i,j)+l) |
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enddo |
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do k=1,4 |
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ew_val(k) = |
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& arrayin(w_ind(i,j)-1,s_ind(i,j)+k-2) |
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& *lagran(1,xG(i,j,bi,bj),px_ind,sp) |
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& +arrayin(w_ind(i,j) ,s_ind(i,j)+k-2) |
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& *lagran(2,xG(i,j,bi,bj),px_ind,sp) |
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& +arrayin(e_ind(i,j) ,s_ind(i,j)+k-2) |
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& *lagran(3,xG(i,j,bi,bj),px_ind,sp) |
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& +arrayin(e_ind(i,j)+1,s_ind(i,j)+k-2) |
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& *lagran(4,xG(i,j,bi,bj),px_ind,sp) |
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arrayout(i,j,bi,bj)=arrayout(i,j,bi,bj) |
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& +ew_val(k)*lagran(k,yG(i,j,bi,bj),py_ind,sp) |
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enddo |
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enddo |
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enddo |
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else |
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stop 'stop in exf_interp.F: interpolation method not supported' |
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endif |
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enddo |
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enddo |
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|
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RETURN |
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END |
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