/[MITgcm]/MITgcm/pkg/exf/exf_interp.F
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Contents of /MITgcm/pkg/exf/exf_interp.F

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Revision 1.10 - (show annotations) (download)
Mon May 2 15:31:46 2005 UTC (19 years ago) by heimbach
Branch: MAIN
CVS Tags: checkpoint57t_post, checkpoint57o_post, checkpoint57v_post, checkpoint57m_post, checkpoint57s_post, checkpoint57k_post, checkpoint57i_post, checkpoint57r_post, checkpoint57h_done, checkpoint57n_post, checkpoint57w_post, checkpoint57p_post, checkpint57u_post, checkpoint57q_post, checkpoint57j_post, checkpoint57h_pre, checkpoint57l_post, checkpoint57h_post
Branch point for: release1_50yr
Changes since 1.9: +0 -3 lines
Remove obsolete EESUPPORT.h which includes mpif.h

1 #include "EXF_OPTIONS.h"
2 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 real*8 function lagran(i,x,a,sp)
13
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 I irecord, xG, yG,
40 I lon_0, lon_inc,
41 I lat_0, lat_inc,
42 I nx_in, ny_in, method, mythid)
43
44 implicit none
45
46 C infile = name of the input file (direct access binary)
47 C filePrec = file precicision (currently not used, assumes real*4)
48 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 C method = 1 for bilinear 2 for bicubic
56 C mythid = thread id
57 C
58
59 #include "SIZE.h"
60 #include "EEPARAMS.h"
61 #include "PARAMS.h"
62
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 _RS xG (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
68 _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
73 C local variables
74 real*8 ne_fac,nw_fac,se_fac,sw_fac
75 integer e_ind(snx,sny),w_ind(snx,sny)
76 integer n_ind(snx,sny),s_ind(snx,sny)
77 real*8 px_ind(4), py_ind(4), ew_val(4)
78 external lagran
79 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 integer i, j, k, l, js, bi, bj, sp, interp_unit
83
84 call exf_interp_read(
85 I infile,
86 I filePrec,
87 O arrayin,
88 I irecord, xG, yG,
89 I lon_0, lon_inc,
90 I lat_0, lat_inc,
91 I nx_in, ny_in, method, mythid)
92
93 _BEGIN_MASTER( myThid )
94
95 C setup input grid
96 do i=-1,nx_in+2
97 x_in(i) = lon_0 + (i-1.)*lon_inc
98 enddo
99 y_in(0) = lat_0 - lat_inc(1)
100 y_in(-1)= lat_0 - 2.*lat_inc(1)
101 y_in(1) = lat_0
102 do j=2,ny_in
103 y_in(j) = y_in(j-1) + lat_inc(j-1)
104 enddo
105 y_in(ny_in+1) = y_in(ny_in) + lat_inc(ny_in-1)
106 y_in(ny_in+2) = y_in(ny_in) + 2.*lat_inc(ny_in-1)
107
108 C enlarge boundary
109 do j=1,ny_in
110 arrayin(0,j) = arrayin(nx_in,j)
111 arrayin(-1,j) = arrayin(nx_in-1,j)
112 arrayin(nx_in+1,j) = arrayin(1,j)
113 arrayin(nx_in+2,j) = arrayin(2,j)
114 enddo
115 do i=-1,nx_in+2
116 arrayin(i,0) = arrayin(i,1)
117 arrayin(i,-1) = arrayin(i,1)
118 arrayin(i,ny_in+1) = arrayin(i,ny_in)
119 arrayin(i,ny_in+2) = arrayin(i,ny_in)
120 enddo
121
122 _END_MASTER( myThid )
123
124 do bj = mybylo(mythid), mybyhi(mythid)
125 do bi = mybxlo(mythid), mybxhi(mythid)
126
127 C check validity of input/output coordinates
128 #ifdef ALLOW_DEBUG
129 if ( debugLevel .ge. debLevB ) then
130 do i=1,snx
131 do j=1,sny
132 if ( xG(i,j,bi,bj) .lt. x_in(0) .or.
133 & xG(i,j,bi,bj) .ge. x_in(nx_in+1) .or.
134 & yG(i,j,bi,bj) .lt. y_in(0) .or.
135 & yG(i,j,bi,bj) .ge. y_in(ny_in+1) ) then
136 print*,'ERROR in S/R EXF_INTERP:'
137 print*,' input grid must encompass output grid.'
138 print*,'i,j,bi,bj' ,i,j,bi,bj
139 print*,'xG,yG' ,xG(i,j,bi,bj),yG(i,j,bi,bj)
140 print*,'nx_in,ny_in' ,nx_in ,ny_in
141 print*,'x_in(0,nx_in+1)',x_in(0) ,x_in(nx_in+1)
142 print*,'y_in(0,ny_in+1)',y_in(0) ,y_in(ny_in+1)
143 STOP ' ABNORMAL END: S/R EXF_INTERP'
144 endif
145 enddo
146 enddo
147 endif
148 #endif /* ALLOW_DEBUG */
149
150 C compute interpolation indices
151 do i=1,snx
152 do j=1,sny
153 if (xG(i,j,bi,bj)-x_in(1) .ge. 0.) then
154 w_ind(i,j) = int((xG(i,j,bi,bj)-x_in(1))/lon_inc) + 1
155 else
156 w_ind(i,j) = int((xG(i,j,bi,bj)-x_in(1))/lon_inc)
157 endif
158 e_ind(i,j) = w_ind(i,j) + 1
159 js = ny_in*.5
160 do while (yG(i,j,bi,bj) .lt. y_in(js))
161 js = (js - 1)*.5
162 enddo
163 do while (yG(i,j,bi,bj) .ge. y_in(js+1))
164 js = js + 1
165 enddo
166 s_ind(i,j) = js
167 n_ind(i,j) = js + 1
168 enddo
169 enddo
170
171 if (method .eq. 1) then
172
173 C bilinear interpolation
174 sp = 2
175 do j=1,sny
176 do i=1,snx
177 arrayout(i,j,bi,bj) = 0.
178 do l=0,1
179 px_ind(l+1) = x_in(w_ind(i,j)+l)
180 py_ind(l+1) = y_in(s_ind(i,j)+l)
181 enddo
182 do k=1,2
183 ew_val(k) = arrayin(w_ind(i,j),s_ind(i,j)+k-1)
184 & *lagran(1,xG(i,j,bi,bj),px_ind,sp)
185 & +arrayin(e_ind(i,j),s_ind(i,j)+k-1)
186 & *lagran(2,xG(i,j,bi,bj),px_ind,sp)
187 arrayout(i,j,bi,bj)=arrayout(i,j,bi,bj)
188 & +ew_val(k)*lagran(k,yG(i,j,bi,bj),py_ind,sp)
189 enddo
190 enddo
191 enddo
192 elseif (method .eq. 2) then
193
194 C bicubic interpolation
195 sp = 4
196 do j=1,sny
197 do i=1,snx
198 arrayout(i,j,bi,bj) = 0.
199 do l=-1,2
200 px_ind(l+2) = x_in(w_ind(i,j)+l)
201 py_ind(l+2) = y_in(s_ind(i,j)+l)
202 enddo
203 do k=1,4
204 ew_val(k) =
205 & arrayin(w_ind(i,j)-1,s_ind(i,j)+k-2)
206 & *lagran(1,xG(i,j,bi,bj),px_ind,sp)
207 & +arrayin(w_ind(i,j) ,s_ind(i,j)+k-2)
208 & *lagran(2,xG(i,j,bi,bj),px_ind,sp)
209 & +arrayin(e_ind(i,j) ,s_ind(i,j)+k-2)
210 & *lagran(3,xG(i,j,bi,bj),px_ind,sp)
211 & +arrayin(e_ind(i,j)+1,s_ind(i,j)+k-2)
212 & *lagran(4,xG(i,j,bi,bj),px_ind,sp)
213 arrayout(i,j,bi,bj)=arrayout(i,j,bi,bj)
214 & +ew_val(k)*lagran(k,yG(i,j,bi,bj),py_ind,sp)
215 enddo
216 enddo
217 enddo
218 else
219 stop 'stop in exf_interp.F: interpolation method not supported'
220 endif
221 enddo
222 enddo
223
224 END

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