/[MITgcm]/MITgcm/pkg/exf/exf_interp.F
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Revision 1.14 - (hide annotations) (download)
Sat Jan 14 20:47:43 2006 UTC (18 years, 4 months ago) by jmc
Branch: MAIN
CVS Tags: checkpoint58e_post, checkpoint58h_post, checkpoint58j_post, checkpoint58f_post, checkpoint58d_post, checkpoint58c_post, checkpoint58a_post, checkpoint58i_post, checkpoint58g_post, checkpoint58b_post
Changes since 1.13: +6 -12 lines
fix for different longitude origin in input field & model grid

1 edhill 1.3 #include "EXF_OPTIONS.h"
2 dimitri 1.1 CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
3     C Flux Coupler using C
4     C Bilinear interpolation of forcing fields C
5     C C
6     C B. Cheng (12/2002) C
7     C C
8     C added Bicubic (bnc 1/2003) C
9     C C
10     CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
11    
12 dimitri 1.2 real*8 function lagran(i,x,a,sp)
13 dimitri 1.1
14     INTEGER i,k,sp
15     _RS x
16     real*8 a(4)
17     real*8 numer,denom
18    
19     numer = 1.D0
20     denom = 1.D0
21    
22     do k=1,sp
23     if ( k .ne. i) then
24     denom = denom*(a(i) - a(k))
25     numer = numer*(x - a(k))
26     endif
27     enddo
28    
29     lagran = numer/denom
30    
31     return
32     end
33    
34    
35     SUBROUTINE exf_interp(
36     I infile,
37     I filePrec,
38     O arrayout,
39 heimbach 1.13 I irecord, xG_in, yG,
40 dimitri 1.2 I lon_0, lon_inc,
41     I lat_0, lat_inc,
42     I nx_in, ny_in, method, mythid)
43 dimitri 1.1
44 dimitri 1.4 implicit none
45    
46 dimitri 1.2 C infile = name of the input file (direct access binary)
47     C filePrec = file precicision (currently not used, assumes real*4)
48 dimitri 1.1 C arrout = output arrays (different for each processor)
49     C irecord = record number in global file
50     C xG,yG = coordinates for output grid
51     C lon_0, lat_0 = lon and lat of sw corner of global input grid
52     C lon_inc = scalar x-grid increment
53     C lat_inc = vector y-grid increments
54     C nx_in, ny_in = input x-grid and y-grid size
55 dimitri 1.2 C method = 1 for bilinear 2 for bicubic
56     C mythid = thread id
57 dimitri 1.1 C
58    
59     #include "SIZE.h"
60     #include "EEPARAMS.h"
61 adcroft 1.7 #include "PARAMS.h"
62 dimitri 1.2
63     C subroutine variables
64     character*(*) infile
65     integer filePrec, irecord, nx_in, ny_in
66     _RL arrayout(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
67 heimbach 1.12 _RS xG_in (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
68 dimitri 1.2 _RS yG (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
69     _RL lon_0, lon_inc
70     _RL lat_0, lat_inc(ny_in-1)
71     integer method, mythid
72 dimitri 1.1
73     C local variables
74 jmc 1.14 c real*8 ne_fac,nw_fac,se_fac,sw_fac
75 dimitri 1.5 integer e_ind(snx,sny),w_ind(snx,sny)
76     integer n_ind(snx,sny),s_ind(snx,sny)
77 dimitri 1.2 real*8 px_ind(4), py_ind(4), ew_val(4)
78 dimitri 1.1 external lagran
79 dimitri 1.2 real*8 lagran
80     real*4 arrayin(-1:nx_in+2 , -1:ny_in+2)
81     real*8 x_in (-1:nx_in+2), y_in(-1:ny_in+2)
82 dimitri 1.5 integer i, j, k, l, js, bi, bj, sp, interp_unit
83 heimbach 1.13 _RS xG(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
84     _RS threeSixtyRS
85     PARAMETER ( threeSixtyRS = 360. )
86 heimbach 1.12
87 jmc 1.14 C put xG in interval [ lon_0 , lon_0+360 [
88 heimbach 1.12 do bj=myByLo(myThid),myByHi(myThid)
89     do bi=myBxLo(myThid),myBxHi(myThid)
90     do j=1-OLy,sNy+OLy
91     do i=1-OLx,sNx+OLx
92 jmc 1.14 xG(i,j,bi,bj) = xG_in(i,j,bi,bj)-lon_0
93     & + threeSixtyRS*2.
94     xG(i,j,bi,bj) = lon_0+mod(xG(i,j,bi,bj),threeSixtyRS)
95 heimbach 1.12 enddo
96     enddo
97     enddo
98     enddo
99 heimbach 1.9
100     call exf_interp_read(
101     I infile,
102     I filePrec,
103     O arrayin,
104     I irecord, xG, yG,
105     I lon_0, lon_inc,
106     I lat_0, lat_inc,
107     I nx_in, ny_in, method, mythid)
108 cnh 1.11 _BARRIER
109 dimitri 1.4
110 cnh 1.11 C _BEGIN_MASTER( myThid )
111 dimitri 1.2
112 dimitri 1.1 C setup input grid
113 dimitri 1.4 do i=-1,nx_in+2
114 jmc 1.14 x_in(i) = lon_0 + (i-1)*lon_inc
115 dimitri 1.4 enddo
116 heimbach 1.12
117 dimitri 1.4 y_in(0) = lat_0 - lat_inc(1)
118     y_in(-1)= lat_0 - 2.*lat_inc(1)
119     y_in(1) = lat_0
120     do j=2,ny_in
121     y_in(j) = y_in(j-1) + lat_inc(j-1)
122     enddo
123     y_in(ny_in+1) = y_in(ny_in) + lat_inc(ny_in-1)
124     y_in(ny_in+2) = y_in(ny_in) + 2.*lat_inc(ny_in-1)
125 dimitri 1.1
126     C enlarge boundary
127 dimitri 1.4 do j=1,ny_in
128     arrayin(0,j) = arrayin(nx_in,j)
129     arrayin(-1,j) = arrayin(nx_in-1,j)
130     arrayin(nx_in+1,j) = arrayin(1,j)
131     arrayin(nx_in+2,j) = arrayin(2,j)
132     enddo
133     do i=-1,nx_in+2
134     arrayin(i,0) = arrayin(i,1)
135     arrayin(i,-1) = arrayin(i,1)
136     arrayin(i,ny_in+1) = arrayin(i,ny_in)
137     arrayin(i,ny_in+2) = arrayin(i,ny_in)
138     enddo
139    
140 cnh 1.11 C _END_MASTER( myThid )
141 dimitri 1.2
142     do bj = mybylo(mythid), mybyhi(mythid)
143     do bi = mybxlo(mythid), mybxhi(mythid)
144    
145     C check validity of input/output coordinates
146 dimitri 1.6 #ifdef ALLOW_DEBUG
147     if ( debugLevel .ge. debLevB ) then
148     do i=1,snx
149     do j=1,sny
150     if ( xG(i,j,bi,bj) .lt. x_in(0) .or.
151     & xG(i,j,bi,bj) .ge. x_in(nx_in+1) .or.
152     & yG(i,j,bi,bj) .lt. y_in(0) .or.
153     & yG(i,j,bi,bj) .ge. y_in(ny_in+1) ) then
154     print*,'ERROR in S/R EXF_INTERP:'
155     print*,' input grid must encompass output grid.'
156     print*,'i,j,bi,bj' ,i,j,bi,bj
157     print*,'xG,yG' ,xG(i,j,bi,bj),yG(i,j,bi,bj)
158     print*,'nx_in,ny_in' ,nx_in ,ny_in
159     print*,'x_in(0,nx_in+1)',x_in(0) ,x_in(nx_in+1)
160     print*,'y_in(0,ny_in+1)',y_in(0) ,y_in(ny_in+1)
161     STOP ' ABNORMAL END: S/R EXF_INTERP'
162     endif
163     enddo
164     enddo
165 dimitri 1.2 endif
166 dimitri 1.6 #endif /* ALLOW_DEBUG */
167 dimitri 1.1
168     C compute interpolation indices
169     do i=1,snx
170 dimitri 1.5 do j=1,sny
171     if (xG(i,j,bi,bj)-x_in(1) .ge. 0.) then
172     w_ind(i,j) = int((xG(i,j,bi,bj)-x_in(1))/lon_inc) + 1
173     else
174     w_ind(i,j) = int((xG(i,j,bi,bj)-x_in(1))/lon_inc)
175     endif
176     e_ind(i,j) = w_ind(i,j) + 1
177 dimitri 1.6 js = ny_in*.5
178 dimitri 1.5 do while (yG(i,j,bi,bj) .lt. y_in(js))
179 dimitri 1.6 js = (js - 1)*.5
180 dimitri 1.5 enddo
181     do while (yG(i,j,bi,bj) .ge. y_in(js+1))
182     js = js + 1
183     enddo
184     s_ind(i,j) = js
185     n_ind(i,j) = js + 1
186 dimitri 1.2 enddo
187 dimitri 1.1 enddo
188    
189 dimitri 1.2 if (method .eq. 1) then
190 dimitri 1.1
191 dimitri 1.2 C bilinear interpolation
192     sp = 2
193     do j=1,sny
194     do i=1,snx
195 dimitri 1.1 arrayout(i,j,bi,bj) = 0.
196 dimitri 1.2 do l=0,1
197 dimitri 1.5 px_ind(l+1) = x_in(w_ind(i,j)+l)
198     py_ind(l+1) = y_in(s_ind(i,j)+l)
199 dimitri 1.1 enddo
200 dimitri 1.2 do k=1,2
201 dimitri 1.5 ew_val(k) = arrayin(w_ind(i,j),s_ind(i,j)+k-1)
202     & *lagran(1,xG(i,j,bi,bj),px_ind,sp)
203     & +arrayin(e_ind(i,j),s_ind(i,j)+k-1)
204     & *lagran(2,xG(i,j,bi,bj),px_ind,sp)
205 dimitri 1.2 arrayout(i,j,bi,bj)=arrayout(i,j,bi,bj)
206 dimitri 1.5 & +ew_val(k)*lagran(k,yG(i,j,bi,bj),py_ind,sp)
207 dimitri 1.1 enddo
208     enddo
209     enddo
210 dimitri 1.2 elseif (method .eq. 2) then
211 dimitri 1.1
212 dimitri 1.2 C bicubic interpolation
213     sp = 4
214     do j=1,sny
215     do i=1,snx
216 dimitri 1.1 arrayout(i,j,bi,bj) = 0.
217 dimitri 1.2 do l=-1,2
218 dimitri 1.5 px_ind(l+2) = x_in(w_ind(i,j)+l)
219     py_ind(l+2) = y_in(s_ind(i,j)+l)
220 dimitri 1.1 enddo
221 dimitri 1.2 do k=1,4
222     ew_val(k) =
223 dimitri 1.5 & arrayin(w_ind(i,j)-1,s_ind(i,j)+k-2)
224     & *lagran(1,xG(i,j,bi,bj),px_ind,sp)
225     & +arrayin(w_ind(i,j) ,s_ind(i,j)+k-2)
226     & *lagran(2,xG(i,j,bi,bj),px_ind,sp)
227     & +arrayin(e_ind(i,j) ,s_ind(i,j)+k-2)
228     & *lagran(3,xG(i,j,bi,bj),px_ind,sp)
229     & +arrayin(e_ind(i,j)+1,s_ind(i,j)+k-2)
230     & *lagran(4,xG(i,j,bi,bj),px_ind,sp)
231 dimitri 1.2 arrayout(i,j,bi,bj)=arrayout(i,j,bi,bj)
232 dimitri 1.5 & +ew_val(k)*lagran(k,yG(i,j,bi,bj),py_ind,sp)
233 dimitri 1.1 enddo
234 dimitri 1.2 enddo
235 dimitri 1.1 enddo
236 dimitri 1.2 else
237     stop 'stop in exf_interp.F: interpolation method not supported'
238     endif
239     enddo
240     enddo
241 dimitri 1.1
242     END

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