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3 michaesp 1
      PROGRAM timeresolution
2
 
3
c     ***********************************************************************
4
c     * Change time resolution of of a trajectory file                      *
5
c     * Michael Sprenger / Winter 2010                                      *
6
c     ***********************************************************************
7
 
8
      implicit none
9
 
10
c     ----------------------------------------------------------------------
11
c     Declaration of variables
12
c     ----------------------------------------------------------------------
13
 
14
c     Parameters
15
      character*80                           inpfile     
16
      character*80                           outfile     
17
      integer                                ntra,otim,ncol
18
      real                                   timeres
19
      character*80                           unit
20
      character*80                           mode
21
      real                                   shift
22
 
23
c     Trajectories
24
      character*80                           vars(100)   
25
      integer                                refdate(6)  
26
      integer                                ntim       
27
      real,allocatable, dimension (:,:,:) :: trainp        
28
      real,allocatable, dimension (:,:,:) :: traout        
29
      real,allocatable, dimension (:)     :: timold,timnew
30
      real,allocatable, dimension (:)     :: fldold,fldnew
31
 
32
c     Numerical constants
33
      real                                   eps
34
      parameter                              (eps=0.001)
35
 
36
c     Auxiliary variables
37
      integer                                inpmode
38
      integer                                outmode
39
      integer                                stat
40
      integer                                fid
41
      integer                                i,j,k
42
      real                                   hhmm,tfrac
43
      real                                   range
44
      integer                                date0(5),date1(5)
45
 
46
c     ----------------------------------------------------------------------
47
c     Parameter handling
48
c     ----------------------------------------------------------------------
49
 
50
c     Read parameters
51
      open(10,file='timeres.param')
52
       read(10,*) inpfile
53
       read(10,*) outfile
54
       read(10,*) ntra,otim,ncol
55
       read(10,*) timeres
56
       read(10,*) unit
57
       read(10,*) mode
58
       read(10,*) shift
59
      close(10)
60
 
61
c     Change unit to hours
62
      if ( unit.eq.'min') then
63
         timeres = 1./60. * timeres
64
         unit    = 'h'
65
      endif
66
 
67
c     Determine the formats
68
      call mode_tra(inpmode,inpfile)
69
      if (inpmode.eq.-1) inpmode=1
70
      call mode_tra(outmode,outfile)
71
      if (outmode.eq.-1) outmode=1
72
 
73
c     ----------------------------------------------------------------------
74
c     Read input trajectory and allocate memory
75
c     ----------------------------------------------------------------------
76
 
77
c     Allocate memory for input trajectories
78
      allocate(trainp(ntra,otim,ncol),stat=stat)
79
      if (stat.ne.0) print*,'*** error allocating array trainp   ***' 
80
      allocate(timold(otim),stat=stat)
81
      if (stat.ne.0) print*,'*** error allocating array timold   ***' 
82
      allocate(fldold(otim),stat=stat)
83
      if (stat.ne.0) print*,'*** error allocating array fldold   ***' 
84
 
85
c     Read inpufile
86
      call ropen_tra(fid,inpfile,ntra,otim,ncol,refdate,vars,inpmode)
87
      call read_tra (fid,trainp,ntra,otim,ncol,inpmode)
88
      call close_tra(fid,inpmode)
89
 
90
c     Check that first four columns correspond to time,lon,lat,p
91
      if ( (vars(1).ne.'time' ).or.
92
     >     (vars(2).ne.'xpos' ).and.(vars(2).ne.'lon' ).or.
93
     >     (vars(3).ne.'ypos' ).and.(vars(3).ne.'lat' ).or.
94
     >     (vars(4).ne.'ppos' ).and.(vars(4).ne.'p'   ) )
95
     >then
96
         print*,' ERROR: problem with input trajectories ...'
97
         stop
98
      endif
99
 
100
c     Convert all times from hhmm to fractional time
101
      do i=1,ntra
102
         do j=1,otim
103
            hhmm = trainp(i,j,1)
104
            call hhmm2frac(hhmm,tfrac)
105
            trainp(i,j,1) = tfrac
106
         enddo
107
      enddo
108
 
109
c     Get the time range in hours
110
      range = ( trainp(1,otim,1) - trainp(1,1,1) ) 
111
 
112
c     If timeres=0, keep the original resolution
113
      if ( abs(timeres).lt.eps ) then
114
         timeres = trainp(1,2,1) - trainp(1,1,1)
115
         print*,'Keeping time resolution',timeres
116
      endif
117
 
118
c     Determine the new number of times
119
      ntim = nint( abs( range ) / timeres ) + 1 
120
 
121
c     Check that the time range and new time resolution are consistent
122
      if ( abs( real(ntim-1) * timeres - abs(range) ).gt.eps ) then
123
         print*,' ERROR: time range and resolution are not compatible'
124
         print*,'   range              = ',range
125
         print*,'   (ntim-1) * timeres = ',real(ntim-1) * timeres
126
         stop
127
      endif
128
 
129
c     Allocate memory for output trajectories
130
      allocate(traout(ntra,ntim,ncol),stat=stat)
131
      if (stat.ne.0) print*,'*** error allocating array trainp   ***' 
132
      allocate(timnew(ntim),stat=stat)
133
      if (stat.ne.0) print*,'*** error allocating array timnew   ***' 
134
      allocate(fldnew(ntim),stat=stat)
135
      if (stat.ne.0) print*,'*** error allocating array fldnew   ***' 
136
 
137
c     ----------------------------------------------------------------------
138
c     Change time resolution
139
c     ----------------------------------------------------------------------
140
 
141
c     Define the old and new times
142
      do i=1,otim
143
         timold(i) = trainp(1,i,1)
144
      enddo
145
      do i=1,ntim
146
         timnew(i) = timold(1) + real(i-1) * timeres
147
      enddo
148
 
149
c     Change time resolution
150
      do i=1,ntra
151
      do k=2,ncol
152
 
153
c        Copy old field
154
         do j=1,otim
155
            fldold(j) = trainp(i,j,k)
156
         enddo
157
 
158
c        Exception: Handle date line problem for longitude
159
         if ( k.eq.2 ) then 
160
            do j=2,otim
161
               if ( (fldold(j-1)-fldold(j)).gt.180. ) then
162
                  fldold(j) = fldold(j) + 360.
163
               else if ( (fldold(j-1)-fldold(j)).lt.-180. ) then
164
                  fldold(j) = fldold(j) - 360.
165
               endif
166
            enddo
167
         endif
168
 
169
c        Cubic spline fitting
170
         if ( mode.eq.'cubic' ) then
171
            call cubicfit (timold,fldold,otim,timnew,fldnew,ntim)
172
         else if (mode.eq.'linear' ) then
173
            call linearfit(timold,fldold,otim,timnew,fldnew,ntim)
174
         endif
175
 
176
c        Exception: Reverse date line handling for longitude
177
         if ( k.eq.2 ) then
178
            do j=1,ntim
179
               if ( fldnew(j).gt.180. ) then
180
                  fldnew(j) = fldnew(j) -360.
181
               else if ( fldnew(j).lt.-180. ) then
182
                  fldnew(j) = fldnew(j) +360.
183
               endif
184
            enddo
185
         endif
186
 
187
c        Save the new field in the output trajectory
188
         do j=1,ntim
189
            traout(i,j,1) = timnew(j)
190
            traout(i,j,k) = fldnew(j)
191
         enddo
192
 
193
      enddo
194
      enddo
195
 
196
c     ----------------------------------------------------------------------
197
c     Shift time axis - change reference date
198
c     ----------------------------------------------------------------------
199
 
200
c     Shift the reference date
201
      date0(1) = refdate(1)
202
      date0(2) = refdate(2)
203
      date0(3) = refdate(3)
204
      date0(4) = refdate(4)
205
      date0(5) = refdate(5)
206
      call newdate (date0,shift,date1)
207
      refdate(1) = date1(1)
208
      refdate(2) = date1(2)
209
      refdate(3) = date1(3)
210
      refdate(4) = date1(4)
211
      refdate(5) = date1(5)
212
 
213
c     Shift the times
214
      do i=1,ntra
215
      do j=1,ntim
216
        traout(i,j,1) = traout(i,j,1) - shift
217
      enddo
218
      enddo
219
 
220
c     ----------------------------------------------------------------------
221
c     Write output trajectory
222
c     ----------------------------------------------------------------------
223
 
224
c     Convert all times from fractional to hhmm time
225
      do i=1,ntra
226
         do j=1,ntim
227
            tfrac = traout(i,j,1)
228
            call frac2hhmm(tfrac,hhmm)
229
            traout(i,j,1) = hhmm
230
         enddo
231
      enddo
232
 
233
c     Write output file
234
      call wopen_tra(fid,outfile,ntra,ntim,ncol,refdate,vars,outmode)
235
      call write_tra(fid,traout,ntra,ntim,ncol,outmode)
236
      call close_tra(fid,outmode)
237
 
238
      end
239
 
240
 
241
c     ********************************************************************
242
c     * REPARAMETERIZATION SUBROUTINES                                   *
243
c     ********************************************************************
244
 
245
c     -------------------------------------------------------------
246
c     Interpolation of the trajectory with linear interpolation
247
c     -------------------------------------------------------------
248
 
249
      SUBROUTINE linearfit (time,lon,n,sptime,splon,spn)
250
 
251
c     Given the curve <time,lon> with <n> data points, fit a
252
c     linear fit to this curve. The new curve is returned in 
253
c     <sptime,splon,spn> with <spn> data points. The parameter
254
c     <spn> specifies on entry the number of interpolated points
255
c     along the curve.
256
 
257
      implicit none
258
 
259
c     Declaration of subroutine parameters
260
      integer n
261
      real    time(n),lon(n)
262
      integer spn
263
      real    sptime(spn),splon(spn)
264
 
265
c     Auxiliary variables
266
      real    dt
267
      real    s
268
      integer i,j,iold
269
      real    order
270
 
271
c     Determine whether the input array is ascending or descending
272
      if (time(1).gt.time(n)) then
273
         order=-1.
274
      else
275
         order= 1.
276
      endif
277
 
278
c     Bring the time array into ascending order
279
      do i=1,n
280
         time(i)=order*time(i)
281
      enddo
282
 
283
c     Prepare the linear interpolation: define the new times
284
      dt=(time(n)-time(1))/real(spn-1)
285
      do i=1,spn
286
         sptime(i)=time(1)+real(i-1)*dt
287
      enddo
288
 
289
c     Do the interpolation
290
      iold = 1
291
      do i=1,spn
292
 
293
c        Decide which interval of the old time series must be taken
294
         do j=iold,n-1
295
            if ( ( sptime(i).ge.time(j  ) ).and.
296
     >           ( sptime(i).lt.time(j+1) ) ) 
297
     >      then
298
               iold = j
299
               exit
300
            endif
301
         enddo
302
 
303
c        Do the linear interpolation
304
         splon(i) = lon(iold) + ( lon(iold+1) - lon(iold) ) * 
305
     >       ( sptime(i) - time(iold) ) / ( time(iold+1) - time(iold) ) 
306
 
307
      enddo
308
 
309
c     Change the time arrays back: original order
310
      do i=1,spn
311
         sptime(i)=order*sptime(i)
312
      enddo
313
      do i=1,n
314
         time(i)=order*time(i)
315
      enddo
316
 
317
      return
318
      end
319
 
320
 
321
c     -------------------------------------------------------------
322
c     Interpolation of the trajectory with a natural cubic spline
323
c     -------------------------------------------------------------
324
 
325
      SUBROUTINE cubicfit (time,lon,n,sptime,splon,spn)
326
 
327
c     Given the curve <time,lon> with <n> data points, fit a
328
c     cubic spline to this curve. The new curve is returned in 
329
c     <sptime,splon,spn> with <spn> data points. The parameter
330
c     <spn> specifies on entry the number of spline interpolated points
331
c     along the curve.
332
 
333
      implicit none
334
 
335
c     Declaration of subroutine parameters
336
      integer n
337
      real    time(n),lon(n)
338
      integer spn
339
      real    sptime(spn),splon(spn)
340
 
341
c     Auxiliary variables
342
      real    y2ax(n)
343
      real    dt
344
      real    s
345
      integer i
346
      real    order
347
 
348
c     Determine whether the input array is ascending or descending
349
      if (time(1).gt.time(n)) then
350
         order=-1.
351
      else
352
         order= 1.
353
      endif
354
 
355
c     Bring the time array into ascending order
356
      do i=1,n
357
         time(i)=order*time(i)
358
      enddo
359
 
360
c     Prepare the (natural) cubic spline interpolation
361
      call spline (time,lon,n,1.e30,1.e30,y2ax)
362
      dt=(time(n)-time(1))/real(spn-1)
363
      do i=1,spn
364
         sptime(i)=time(1)+real(i-1)*dt
365
      enddo
366
 
367
c     Do the spline interpolation
368
      do i=1,spn
369
         call splint(time,lon,y2ax,n,sptime(i),s)
370
         splon(i)=s
371
      enddo
372
 
373
c     Change the time arrays back
374
      do i=1,spn
375
         sptime(i)=order*sptime(i)
376
      enddo
377
      do i=1,n
378
         time(i)=order*time(i)
379
      enddo
380
 
381
      return
382
      end
383
 
384
c     -------------------------------------------------------------
385
c     Basic routines for spline interpolation (Numerical Recipes)
386
c     -------------------------------------------------------------
387
 
388
      SUBROUTINE spline(x,y,n,yp1,ypn,y2)
389
      INTEGER n,NMAX
390
      REAL yp1,ypn,x(n),y(n),y2(n)
391
      PARAMETER (NMAX=500)
392
      INTEGER i,k
393
      REAL p,qn,sig,un,u(NMAX)
394
      if (yp1.gt..99e30) then
395
        y2(1)=0.
396
        u(1)=0.
397
      else
398
        y2(1)=-0.5
399
        u(1)=(3./(x(2)-x(1)))*((y(2)-y(1))/(x(2)-x(1))-yp1)
400
      endif
401
      do 11 i=2,n-1
402
        sig=(x(i)-x(i-1))/(x(i+1)-x(i-1))
403
        p=sig*y2(i-1)+2.
404
        y2(i)=(sig-1.)/p
405
        u(i)=(6.*((y(i+1)-y(i))/(x(i+
406
     *1)-x(i))-(y(i)-y(i-1))/(x(i)-x(i-1)))/(x(i+1)-x(i-1))-sig*
407
     *u(i-1))/p
408
11    continue
409
      if (ypn.gt..99e30) then
410
        qn=0.
411
        un=0.
412
      else
413
        qn=0.5
414
        un=(3./(x(n)-x(n-1)))*(ypn-(y(n)-y(n-1))/(x(n)-x(n-1)))
415
      endif
416
      y2(n)=(un-qn*u(n-1))/(qn*y2(n-1)+1.)
417
      do 12 k=n-1,1,-1
418
        y2(k)=y2(k)*y2(k+1)+u(k)
419
12    continue
420
      return
421
      END
422
 
423
      SUBROUTINE splint(xa,ya,y2a,n,x,y)
424
      INTEGER n
425
      REAL x,y,xa(n),y2a(n),ya(n)
426
      INTEGER k,khi,klo
427
      REAL a,b,h
428
      klo=1
429
      khi=n
430
1     if (khi-klo.gt.1) then
431
        k=(khi+klo)/2
432
        if(xa(k).gt.x)then
433
          khi=k
434
        else
435
          klo=k
436
        endif
437
      goto 1
438
      endif
439
      h=xa(khi)-xa(klo)
440
      if (h.eq.0.) then
441
         print*, 'bad xa input in splint'
442
         stop
443
      endif
444
      a=(xa(khi)-x)/h
445
      b=(x-xa(klo))/h
446
      y=a*ya(klo)+b*ya(khi)+((a**3-a)*y2a(klo)+(b**3-b)*y2a(khi))*(h**
447
     *2)/6.
448
      return
449
      END
450
 
451
 
452