/[MITgcm]/MITgcm/pkg/exf/exf_interp.F
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Revision 1.15 - (hide annotations) (download)
Fri Jun 30 12:05:42 2006 UTC (17 years, 11 months ago) by dimitri
Branch: MAIN
Changes since 1.14: +51 -14 lines
o pkg/exf modifications to interpolation and rotation routines for more
   reasonable treatment of North Pole singularity: for tracers North Pole
   value is set to northernmost zonal-mean value, for zonal velocity it is
   set to zero, and for meridional velocity it is set to northernmost value.

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 1.15 C method = 1,11,21 for bilinear; 2,12,22 for bicubic
56     C 1,2 for tracer; 11,12 for U; 21,22 for V
57 dimitri 1.2 C mythid = thread id
58 dimitri 1.1 C
59    
60     #include "SIZE.h"
61     #include "EEPARAMS.h"
62 adcroft 1.7 #include "PARAMS.h"
63 dimitri 1.2
64     C subroutine variables
65     character*(*) infile
66     integer filePrec, irecord, nx_in, ny_in
67     _RL arrayout(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
68 heimbach 1.12 _RS xG_in (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
69 dimitri 1.2 _RS yG (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
70     _RL lon_0, lon_inc
71     _RL lat_0, lat_inc(ny_in-1)
72     integer method, mythid
73 dimitri 1.1
74     C local variables
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 dimitri 1.15 _RS threeSixtyRS, NorthValue
85 heimbach 1.13 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 dimitri 1.15 I infile, filePrec,
102 heimbach 1.9 O arrayin,
103 dimitri 1.15 I irecord, nx_in, ny_in, mythid)
104 cnh 1.11 _BARRIER
105 dimitri 1.4
106 cnh 1.11 C _BEGIN_MASTER( myThid )
107 dimitri 1.2
108 dimitri 1.1 C setup input grid
109 dimitri 1.4 do i=-1,nx_in+2
110 jmc 1.14 x_in(i) = lon_0 + (i-1)*lon_inc
111 dimitri 1.4 enddo
112 heimbach 1.12
113 dimitri 1.4 y_in(0) = lat_0 - lat_inc(1)
114     y_in(-1)= lat_0 - 2.*lat_inc(1)
115     y_in(1) = lat_0
116     do j=2,ny_in
117     y_in(j) = y_in(j-1) + lat_inc(j-1)
118     enddo
119 dimitri 1.15 c y_in(ny_in+1) = y_in(ny_in) + lat_inc(ny_in-1)
120     c y_in(ny_in+2) = y_in(ny_in) + 2.*lat_inc(ny_in-1)
121     y_in(ny_in+1) = min( y_in(ny_in) + lat_inc(ny_in-1), 90 )
122     y_in(ny_in+2) = min( y_in(ny_in) + 2.*lat_inc(ny_in-1), 90)
123 dimitri 1.1
124     C enlarge boundary
125 dimitri 1.4 do j=1,ny_in
126     arrayin(0,j) = arrayin(nx_in,j)
127     arrayin(-1,j) = arrayin(nx_in-1,j)
128     arrayin(nx_in+1,j) = arrayin(1,j)
129     arrayin(nx_in+2,j) = arrayin(2,j)
130     enddo
131     do i=-1,nx_in+2
132     arrayin(i,0) = arrayin(i,1)
133     arrayin(i,-1) = arrayin(i,1)
134     arrayin(i,ny_in+1) = arrayin(i,ny_in)
135     arrayin(i,ny_in+2) = arrayin(i,ny_in)
136     enddo
137    
138 dimitri 1.15 C For tracer (method=1,2) set to northernmost zonal-mean value
139     C at 90N to avoid sharp zonal gradients near the Pole.
140     C For U (method=11,12) set to zero at 90N to minimize velocity
141     C gradient at North Pole
142     C For V (method=11,12) set to northernmost zonal value at 90N,
143     C as is already done above in order to allow cross-PoleArctic flow
144     if (y_in(ny_in+1).eq.90) then
145     if (method.eq.1 .or. method.eq.2) then
146     NorthValue = 0
147     do i=1,nx_in
148     NorthValue = NorthValue + arrayin(i,ny_in)
149     enddo
150     NorthValue = NorthValue / nx_in
151     do i=-1,nx_in+2
152     arrayin(i,ny_in+1) = NorthValue
153     enddo
154     elseif (method.eq.11 .or. method.eq.12) then
155     do i=-1,nx_in+2
156     arrayin(i,ny_in+1) = 0
157     enddo
158     endif
159     endif
160     if (y_in(ny_in+2).eq.90) then
161     if (method.eq.1 .or. method.eq.2) then
162     NorthValue = 0
163     do i=1,nx_in
164     NorthValue = NorthValue + arrayin(i,ny_in)
165     enddo
166     NorthValue = NorthValue / nx_in
167     do i=-1,nx_in+2
168     arrayin(i,ny_in+2) = NorthValue
169     enddo
170     elseif (method.eq.11 .or. method.eq.12) then
171     do i=-1,nx_in+2
172     arrayin(i,ny_in+2) = 0
173     enddo
174     endif
175     endif
176    
177 cnh 1.11 C _END_MASTER( myThid )
178 dimitri 1.15
179 dimitri 1.2 do bj = mybylo(mythid), mybyhi(mythid)
180     do bi = mybxlo(mythid), mybxhi(mythid)
181    
182     C check validity of input/output coordinates
183 dimitri 1.6 #ifdef ALLOW_DEBUG
184     if ( debugLevel .ge. debLevB ) then
185     do i=1,snx
186     do j=1,sny
187     if ( xG(i,j,bi,bj) .lt. x_in(0) .or.
188     & xG(i,j,bi,bj) .ge. x_in(nx_in+1) .or.
189     & yG(i,j,bi,bj) .lt. y_in(0) .or.
190     & yG(i,j,bi,bj) .ge. y_in(ny_in+1) ) then
191     print*,'ERROR in S/R EXF_INTERP:'
192     print*,' input grid must encompass output grid.'
193     print*,'i,j,bi,bj' ,i,j,bi,bj
194     print*,'xG,yG' ,xG(i,j,bi,bj),yG(i,j,bi,bj)
195     print*,'nx_in,ny_in' ,nx_in ,ny_in
196     print*,'x_in(0,nx_in+1)',x_in(0) ,x_in(nx_in+1)
197     print*,'y_in(0,ny_in+1)',y_in(0) ,y_in(ny_in+1)
198     STOP ' ABNORMAL END: S/R EXF_INTERP'
199     endif
200     enddo
201     enddo
202 dimitri 1.2 endif
203 dimitri 1.6 #endif /* ALLOW_DEBUG */
204 dimitri 1.1
205     C compute interpolation indices
206     do i=1,snx
207 dimitri 1.5 do j=1,sny
208     if (xG(i,j,bi,bj)-x_in(1) .ge. 0.) then
209     w_ind(i,j) = int((xG(i,j,bi,bj)-x_in(1))/lon_inc) + 1
210     else
211     w_ind(i,j) = int((xG(i,j,bi,bj)-x_in(1))/lon_inc)
212     endif
213     e_ind(i,j) = w_ind(i,j) + 1
214 dimitri 1.6 js = ny_in*.5
215 dimitri 1.5 do while (yG(i,j,bi,bj) .lt. y_in(js))
216 dimitri 1.6 js = (js - 1)*.5
217 dimitri 1.5 enddo
218     do while (yG(i,j,bi,bj) .ge. y_in(js+1))
219     js = js + 1
220     enddo
221     s_ind(i,j) = js
222     n_ind(i,j) = js + 1
223 dimitri 1.2 enddo
224 dimitri 1.1 enddo
225    
226 dimitri 1.15 if (method.eq.1 .or. method.eq.11 .or. method.eq.21) then
227 dimitri 1.1
228 dimitri 1.2 C bilinear interpolation
229     sp = 2
230     do j=1,sny
231     do i=1,snx
232 dimitri 1.1 arrayout(i,j,bi,bj) = 0.
233 dimitri 1.2 do l=0,1
234 dimitri 1.5 px_ind(l+1) = x_in(w_ind(i,j)+l)
235     py_ind(l+1) = y_in(s_ind(i,j)+l)
236 dimitri 1.1 enddo
237 dimitri 1.2 do k=1,2
238 dimitri 1.5 ew_val(k) = arrayin(w_ind(i,j),s_ind(i,j)+k-1)
239     & *lagran(1,xG(i,j,bi,bj),px_ind,sp)
240     & +arrayin(e_ind(i,j),s_ind(i,j)+k-1)
241     & *lagran(2,xG(i,j,bi,bj),px_ind,sp)
242 dimitri 1.2 arrayout(i,j,bi,bj)=arrayout(i,j,bi,bj)
243 dimitri 1.5 & +ew_val(k)*lagran(k,yG(i,j,bi,bj),py_ind,sp)
244 dimitri 1.1 enddo
245     enddo
246     enddo
247 dimitri 1.15 elseif (method .eq. 2 .or. method.eq.12 .or. method.eq.22) then
248 dimitri 1.1
249 dimitri 1.2 C bicubic interpolation
250     sp = 4
251     do j=1,sny
252     do i=1,snx
253 dimitri 1.1 arrayout(i,j,bi,bj) = 0.
254 dimitri 1.2 do l=-1,2
255 dimitri 1.5 px_ind(l+2) = x_in(w_ind(i,j)+l)
256     py_ind(l+2) = y_in(s_ind(i,j)+l)
257 dimitri 1.1 enddo
258 dimitri 1.2 do k=1,4
259     ew_val(k) =
260 dimitri 1.5 & arrayin(w_ind(i,j)-1,s_ind(i,j)+k-2)
261     & *lagran(1,xG(i,j,bi,bj),px_ind,sp)
262     & +arrayin(w_ind(i,j) ,s_ind(i,j)+k-2)
263     & *lagran(2,xG(i,j,bi,bj),px_ind,sp)
264     & +arrayin(e_ind(i,j) ,s_ind(i,j)+k-2)
265     & *lagran(3,xG(i,j,bi,bj),px_ind,sp)
266     & +arrayin(e_ind(i,j)+1,s_ind(i,j)+k-2)
267     & *lagran(4,xG(i,j,bi,bj),px_ind,sp)
268 dimitri 1.2 arrayout(i,j,bi,bj)=arrayout(i,j,bi,bj)
269 dimitri 1.5 & +ew_val(k)*lagran(k,yG(i,j,bi,bj),py_ind,sp)
270 dimitri 1.1 enddo
271 dimitri 1.2 enddo
272 dimitri 1.1 enddo
273 dimitri 1.2 else
274     stop 'stop in exf_interp.F: interpolation method not supported'
275     endif
276     enddo
277     enddo
278 dimitri 1.1
279     END

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