source: trunk/LMDZ.MARS/util/extract.F90 @ 2921

Last change on this file since 2921 was 2571, checked in by abierjon, 3 years ago

Mars GCM:
Clarify the description of extract

SF+AB

File size: 23.2 KB
Line 
1program extract
2
3! program to extract (ie: interpolates) pointwise values of an atmospheric
4! variable from a 'zrecast'ed diagfi file (works if altitude is geometrical
5! height or a pressure vertical coordinates)
6! user has to specify:
7! - name of input file
8! - date (in sols) offset wrt the input file (e.g. if the input file "begins"
9!   at Ls=0, then the offset is 0; if the input file begins at Ls=90, the
10!   offset date corresponding to the first 3 months is 61+66+66=193 sols, etc.)
11!   NB: that means the input file must have its "Time" coordinate in sols
12! - the "extraction mode":
13!      1: extract individual values; user will specify values of
14!         lon lat alt Ls LT (all on a same line)
15!         on as many lines as there are sought values
16!      2: extract a profile: user will specify on a first line the values of
17!         lon lat Ls LT (all on a same line)
18!         and then only specify values of altitudes (m or Pa depending on the
19!         coordinate in the input file), one per line, at which values are
20!         sought
21! - output values are sent to (ASCII) output file 'infile_var_.dat', where
22!   'infile' is the input file name (without trailing '.nc') and
23!   'var' is the sought variable, for extraction mode 1 as
24!   lines of "lon lat alt Ls LT value" and for a profile (extraction mode 2)
25!   as lines of "alt value"
26!
27!  NB: If there is no data to do an appropriate interpolation to extract
28!      the sought value, then a "missing_value" (taken from the variable's
29!      attribute in the input file, most likely -9.99E33) is returned.
30!
31! EM. Sept. 2011
32
33use netcdf
34implicit none
35
36! Input file:
37character(len=256) :: infile
38character(len=256) :: outfile
39
40character (len=256) :: text ! to store some text
41character (len=64) :: varname ! to store the name of the variable to retreive
42
43! NetCDF stuff
44integer :: status ! NetCDF return code
45integer :: inid ! NetCDF file IDs
46integer :: varid ! to store the ID of a variable
47integer :: lat_dimid,lon_dimid,alt_dimid,time_dimid
48integer :: datashape(4)
49
50real,dimension(:),allocatable :: longitude ! longitude
51integer lonlen ! # of grid points along longitude
52real,dimension(:),allocatable :: latitude ! latitude
53integer latlen ! # of grid points along latitude
54real,dimension(:),allocatable :: altitude ! can be geometric heights or pressure
55integer altlen ! # of grid point along altitude
56real,dimension(:),allocatable :: time ! time
57integer timelen ! # of points along time
58character :: alttype ! altitude coord. type:'z' (altitude, m) 'p' (pressure, Pa)
59real,dimension(:,:,:,:),allocatable :: field
60real :: missing_value ! value to denote non-existant data
61real :: starttimeoffset ! offset (in sols) wrt Ls=0 of sol 0 in file
62integer :: extract_mode ! 1: point-by-point extraction 2: extract a profile 
63
64! point at which data is sought:
65real :: lon,lat,alt,Ls,LT,value
66real :: sol ! sol GCM date corresponding to sought Ls and LT
67
68integer :: nb
69
70!===============================================================================
71! 1.1 Input file
72!===============================================================================
73
74write(*,*) ""
75write(*,*) " Program valid for diagfi.nc or concatnc.nc files"
76write(*,*) "  processed by zrecast "
77write(*,*) " Enter input file name:"
78
79read(*,'(a)') infile
80write(*,*) ""
81
82! open input file
83status=nf90_open(infile,NF90_NOWRITE,inid)
84if (status.ne.nf90_noerr) then
85  write(*,*)"Failed to open datafile ",trim(infile)
86  write(*,*)trim(nf90_strerror(status))
87 stop
88endif
89
90write(*,*) " Beginning date of the file?"
91write(*,*) " (i.e. number of sols since Ls=0 that the Time=0.0 in the input"
92write(*,*) "  file corresponds to)"
93read(*,*) starttimeoffset
94
95write(*,*) " Extraction mode?"
96write(*,*) " ( 1: pointwise extraction , 2: profile extraction)"
97read(*,*,iostat=status) extract_mode
98if ((status.ne.0).or.(extract_mode.lt.1) &
99                 .or.(extract_mode.gt.2)) then
100  write(*,*) "Error: invalid extraction mode:",extract_mode
101  stop
102endif
103
104!===============================================================================
105! 1.2 Input variable to extract
106!===============================================================================
107
108write(*,*) "Enter variable to extract:"
109read(*,*) varname
110! check that input file contains that variable
111status=nf90_inq_varid(inid,trim(varname),varid)
112if (status.ne.nf90_noerr) then
113  write(*,*) "Failed to find variable ",trim(varname)," in ",trim(infile)
114  write(*,*)trim(nf90_strerror(status))
115  write(*,*) " Might as well stop here."
116  stop
117endif
118
119!===============================================================================
120! 1.3 Get grids for dimensions lon,lat,alt,time
121!===============================================================================
122
123! latitude
124status=nf90_inq_dimid(inid,"latitude",lat_dimid)
125if (status.ne.nf90_noerr) then
126  write(*,*)"Failed to find latitude dimension"
127  write(*,*)trim(nf90_strerror(status))
128 stop
129endif
130status=nf90_inquire_dimension(inid,lat_dimid,len=latlen)
131if (status.ne.nf90_noerr) then
132  write(*,*)"Failed to find latitude length"
133  write(*,*)trim(nf90_strerror(status))
134endif
135allocate(latitude(latlen))
136status=nf90_inq_varid(inid,"latitude",varid)
137if (status.ne.nf90_noerr) then
138  write(*,*) "Failed to find latitude ID"
139  write(*,*)trim(nf90_strerror(status))
140  stop
141endif
142! read latitude
143status=nf90_get_var(inid,varid,latitude)
144if (status.ne.nf90_noerr) then
145  write(*,*) "Failed to load latitude"
146  write(*,*)trim(nf90_strerror(status))
147  stop
148endif
149
150!longitude
151status=nf90_inq_dimid(inid,"longitude",lon_dimid)
152if (status.ne.nf90_noerr) then
153  write(*,*)"Failed to find longitude dimension"
154  write(*,*)trim(nf90_strerror(status))
155 stop
156endif
157status=nf90_inquire_dimension(inid,lon_dimid,len=lonlen)
158if (status.ne.nf90_noerr) then
159  write(*,*)"Failed to find longitude length"
160  write(*,*)trim(nf90_strerror(status))
161endif
162allocate(longitude(lonlen))
163status=nf90_inq_varid(inid,"longitude",varid)
164if (status.ne.nf90_noerr) then
165  write(*,*) "Failed to find longitude ID"
166  write(*,*)trim(nf90_strerror(status))
167  stop
168endif
169! read longitude
170status=nf90_get_var(inid,varid,longitude)
171if (status.ne.nf90_noerr) then
172  write(*,*) "Failed to load longitude"
173  write(*,*)trim(nf90_strerror(status))
174  stop
175endif
176
177!time
178status=nf90_inq_dimid(inid,"Time",time_dimid)
179if (status.ne.nf90_noerr) then
180  write(*,*)"Failed to find Time dimension"
181  write(*,*)trim(nf90_strerror(status))
182 stop
183endif
184status=nf90_inquire_dimension(inid,time_dimid,len=timelen)
185if (status.ne.nf90_noerr) then
186  write(*,*)"Failed to find Time length"
187  write(*,*)trim(nf90_strerror(status))
188endif
189allocate(time(timelen))
190status=nf90_inq_varid(inid,"Time",varid)
191if (status.ne.nf90_noerr) then
192  write(*,*) "Failed to find Time ID"
193  write(*,*)trim(nf90_strerror(status))
194  stop
195endif
196! read Time
197status=nf90_get_var(inid,varid,time)
198if (status.ne.nf90_noerr) then
199  write(*,*) "Failed to load Time"
200  write(*,*)trim(nf90_strerror(status))
201  stop
202endif
203! add the offset to time(:)
204time(:)=time(:)+starttimeoffset
205
206!altitude
207status=nf90_inq_dimid(inid,"altitude",alt_dimid)
208if (status.ne.nf90_noerr) then
209  write(*,*)"Failed to find altitude dimension"
210  write(*,*)trim(nf90_strerror(status))
211 stop
212endif
213status=nf90_inquire_dimension(inid,alt_dimid,len=altlen)
214if (status.ne.nf90_noerr) then
215  write(*,*)"Failed to find altitude length"
216  write(*,*)trim(nf90_strerror(status))
217endif
218allocate(altitude(altlen))
219status=nf90_inq_varid(inid,"altitude",varid)
220if (status.ne.nf90_noerr) then
221  write(*,*) "Failed to find altitude ID"
222  write(*,*)trim(nf90_strerror(status))
223  stop
224endif
225! read altitude
226status=nf90_get_var(inid,varid,altitude)
227if (status.ne.nf90_noerr) then
228  write(*,*) "Failed to load altitude"
229  write(*,*)trim(nf90_strerror(status))
230  stop
231endif
232! check altitude attribute "units" to find out altitude type
233status=nf90_get_att(inid,varid,"units",text)
234if (status.ne.nf90_noerr) then
235  write(*,*) "Failed to load altitude units attribute"
236  write(*,*)trim(nf90_strerror(status))
237  stop
238else
239  if (trim(text).eq."Pa") then
240    alttype="p" ! pressure coordinate
241  else if (trim(text).eq."m") then
242    alttype="z" ! altitude coordinate
243  else
244    write(*,*)" I do not understand this unit ",trim(text)," for altitude!"
245    stop
246  endif
247endif
248
249!===============================================================================
250! 1.3 Get input dataset
251!===============================================================================
252status=nf90_inq_varid(inid,trim(varname),varid)
253if (status.ne.nf90_noerr) then
254  write(*,*) "Failed to find variable ",trim(varname)," in ",trim(infile)
255  write(*,*)trim(nf90_strerror(status))
256  write(*,*) " Might as well stop here."
257  stop
258endif
259
260! sanity checks on the variable
261status=nf90_inquire_variable(inid,varid,ndims=nb,dimids=datashape)
262if (status.ne.nf90_noerr) then
263  write(*,*) "Failed to obtain information on variable ",trim(varname)
264  write(*,*)trim(nf90_strerror(status))
265  write(*,*) " Might as well stop here."
266  stop
267else
268  ! check that it is a 4D variable
269  if (nb.ne.4) then
270    write(*,*) "Error, expected a 4D (lon-lat-alt-time) variable!"
271    stop
272  endif
273  ! check that its dimensions are indeed lon,lat,alt,time
274  if (datashape(1).ne.lon_dimid) then
275    write(*,*) "Error, expected first dimension to be longitude!"
276    stop
277  endif
278  if (datashape(2).ne.lat_dimid) then
279    write(*,*) "Error, expected second dimension to be latitude!"
280    stop
281  endif
282  if (datashape(3).ne.alt_dimid) then
283    write(*,*) "Error, expected third dimension to be altitude!"
284    stop
285  endif
286  if (datashape(4).ne.time_dimid) then
287    write(*,*) "Error, expected fourth dimension to be time!"
288    stop
289  endif
290endif
291
292allocate(field(lonlen,latlen,altlen,timelen))
293
294! load dataset
295status=nf90_get_var(inid,varid,field)
296if (status.ne.nf90_noerr) then
297  write(*,*) "Failed to load ",trim(varname)
298  write(*,*)trim(nf90_strerror(status))
299  stop
300else
301  write(*,*) "Loaded ",trim(varname)
302endif
303! get dataset's missing_value attribute
304status=nf90_get_att(inid,varid,"missing_value",missing_value)
305if (status.ne.nf90_noerr) then
306  write(*,*) "Failed to load missing_value attribute"
307  write(*,*)trim(nf90_strerror(status))
308  stop
309else
310  write(*,'("  with missing_value attribute : ",1pe12.5)') missing_value
311endif
312
313!===============================================================================
314! 2. Process and interpolate
315!===============================================================================
316
317!===============================================================================
318! 2.1 Create output file
319!===============================================================================
320
321outfile=trim(infile(1:index(infile,".nc",back=.true.)-1))//"_"//&
322        trim(varname)//".dat"
323open(42,file=outfile,form="formatted")
324write(*,*) "Output file is: ",trim(outfile)
325
326!===============================================================================
327! 2.2 Extract values
328!===============================================================================
329
330if (extract_mode==1) then ! pointwise extraction
331 write(*,*) " Enter values of: lon lat alt Ls LT (all on the same line,"
332 write(*,*) "                    using as many lines as sought data values)"
333 write(*,*) "    (enter anything else, e.g. blank line, nonesense,... to quit)"
334else ! extract_mode==2 , profile extraction
335 write(*,*) " Enter values of: lon lat Ls LT (all on the same line)"
336 read(*,*) lon,lat,Ls,LT
337 write(*,*) " Enter values of altitude (one per line)"
338 write(*,*) "    (enter anything else, e.g. blank line, nonesense,... to quit)"
339endif
340do
341  ! 2.1 read coordinates and do some sanity checks
342  text="" !initialize text to empty string
343  read(*,'(a)') text ! store input as text (to spot empty input line)
344  if (len_trim(adjustl(text)).eq.0) exit
345 
346  if (extract_mode==1) then
347    read(text,*,iostat=status) lon,lat,alt,Ls,LT
348    ! Ls in degrees, LT (local true solar time) in hours, i.e.  in [0:24]
349  else ! extract_mode==2 , read alt only
350    read(text,*,iostat=status) alt
351  endif
352  if (status.ne.0) exit
353
354  if ((lon.lt.-360.).or.(lon.gt.360.)) then
355    write(*,*) "Unexpected value for lon: ",lon
356    stop
357  endif
358  ! we want lon in [-180:180]
359  if (lon.lt.-180.) lon=lon+360.
360  if (lon.gt.180.) lon=lon-360.
361 
362  if ((lat.lt.-90.).or.(lat.gt.90.)) then
363    write(*,*) "Unexpected value for lat: ",lat
364    stop
365  endif
366 
367  if ((Ls.lt.0.).or.(Ls.gt.360.)) then
368    write(*,*) "Unexpected value for Ls: ",Ls
369    stop
370  endif
371 
372  if ((LT.lt.0.).or.(LT.gt.24.)) then
373    write(*,*) "Unexpected value for LT: ",LT
374    stop
375  endif
376 
377  ! 2.2 compute GCM sol date corresponding to sought  Ls and LT
378  call ls2sol(Ls,sol)
379  !shift 'sol' decimal part to ensure a compatible LT with the desired one
380  sol=floor(sol)+(LT-lon/15.)/24.
381  ! handle bordeline cases:
382  if (sol.gt.669) sol=sol-669
383  if (sol.lt.0) sol=sol+669
384 
385!  write(*,*) " Ls=",Ls," LT=",LT," => sol=",sol
386 
387  ! 2.3 do the interpolation
388  call extraction(lon,lat,alt,sol,&
389                  lonlen,latlen,altlen,timelen,&
390                  longitude,latitude,altitude,time,&
391                  field,missing_value,alttype,varname,value)
392  ! 2.4 Write value to output
393  if (extract_mode==1) then ! pointwise extraction
394    write(42,'(6(1x,1pe12.5))')lon,lat,alt,Ls,LT,value
395  else ! profile
396    write(42,'(6(1x,1pe12.5))')alt,value
397  endif
398enddo ! of do while
399
400! close output file
401close(42)
402
403end program extract
404
405!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
406subroutine extraction(lon,lat,alt,sol,&
407                  lonlen,latlen,altlen,timelen,&
408                  longitude,latitude,altitude,time,&
409                  field,missing_value,alttype,varname,value)
410
411implicit none
412! Arguments:
413real,intent(in) :: lon  ! sought longitude (deg, in [-180:180])
414real,intent(in) :: lat  ! sought latitude (deg, in [-90:90])
415real,intent(in) :: alt  ! sought altitude (m or Pa)
416real,intent(in) :: sol  ! sought date (sols)
417integer,intent(in) :: lonlen
418integer,intent(in) :: latlen
419integer,intent(in) :: altlen
420integer,intent(in) :: timelen
421real,intent(in) :: longitude(lonlen)
422real,intent(in) :: latitude(latlen)
423real,intent(in) :: altitude(altlen)
424real,intent(in) :: time(timelen)
425real,intent(in) :: field(lonlen,latlen,altlen,timelen)
426real,intent(in) :: missing_value ! default value in GCM file for "no data"
427character,intent(in) :: alttype ! altitude coord. type:'z' (altitude, m)
428                                !                      'p' (pressure, Pa)
429character(len=*),intent(in) :: varname ! variable name (in GCM file)
430real,intent(out) :: value
431
432! Local variables:
433real,save :: prev_lon=-99 ! previous value of 'lon' routine was called with
434real,save :: prev_lat=-99 ! previous value of 'lat' routine was called with
435real,save :: prev_alt=-9.e20 ! ! previous value of 'alt'
436real,save :: prev_sol=-99 ! previous value of 'sol' routine was called with
437
438! encompasing indexes:
439integer,save :: ilon_inf=-1,ilon_sup=-1 ! along longitude
440integer,save :: ilat_inf=-1,ilat_sup=-1 ! along latitude
441integer,save :: ialt_inf=-1,ialt_sup=-1 ! along altitude
442integer,save :: itim_inf=-1,itim_sup=-1 ! along time
443
444! intermediate interpolated values
445real :: t_interp(2,2,2) ! after time interpolation
446real :: zt_interp(2,2) ! after altitude interpolation
447real :: yzt_interp(2) ! after latitude interpolation
448real :: coeff ! interpolation coefficient
449
450integer :: i
451
452! By default, set value to missing_value
453value=missing_value
454
455! 1. Find encompassing indexes
456if (lon.ne.prev_lon) then
457  do i=1,lonlen-1
458    if (longitude(i).le.lon) then
459      ilon_inf=i
460    else
461      exit
462    endif
463  enddo
464  ilon_sup=ilon_inf+1
465endif ! of if (lon.ne.prev_lon)
466!write(*,*) 'ilon_inf=',ilon_inf," longitude(ilon_inf)=",longitude(ilon_inf)
467
468if (lat.ne.prev_lat) then
469  ! recall that latitudes start from north pole
470  do i=1,latlen-1
471    if (latitude(i).ge.lat) then
472      ilat_inf=i
473    else
474      exit
475    endif
476  enddo
477  ilat_sup=ilat_inf+1
478endif ! of if (lat.ne.prev_lat)
479!write(*,*) 'ilat_inf=',ilat_inf," latitude(ilat_inf)=",latitude(ilat_inf)
480
481if (alt.ne.prev_alt) then
482  if (alttype.eq.'p') then ! pressures are ordered from max to min
483    !handle special case for alt not in the altitude(1:altlen) interval
484    if ((alt.gt.altitude(1)).or.(alt.lt.altitude(altlen))) then
485      ialt_inf=-1
486      ialt_sup=-1
487      ! return to main program (with value=missing_value)
488      return
489    else ! general case
490      do i=1,altlen-1
491        if (altitude(i).ge.alt) then
492          ialt_inf=i
493        else
494          exit
495        endif
496      enddo
497      ialt_sup=ialt_inf+1
498    endif ! of if ((alt.gt.altitude(1)).or.(alt.lt.altitude(altlen)))
499  else ! altitudes (m) are ordered from min to max
500    !handle special case for alt not in the altitude(1:altlen) interval
501    if ((alt.lt.altitude(1)).or.(alt.gt.altitude(altlen))) then
502      ialt_inf=-1
503      ialt_sup=-1
504      ! return to main program (with value=missing_value)
505      return
506    else ! general case
507      do i=1,altlen-1
508        if (altitude(i).le.alt) then
509          ialt_inf=i
510        else
511          exit
512        endif
513      enddo
514      ialt_sup=ialt_inf+1
515    endif ! of if ((alt.lt.altitude(1)).or.(alt.gt.altitude(altlen)))
516  endif ! of if (alttype.eq.'p')
517endif ! of if (alt.ne.prev_alt)
518!write(*,*) 'ialt_inf=',ialt_inf," altitude(ialt_inf)=",altitude(ialt_inf)
519
520if (sol.ne.prev_sol) then
521  !handle special case for sol not in the time(1):time(timenlen) interval
522  if ((sol.lt.time(1)).or.(sol.gt.time(timelen))) then
523    itim_inf=-1
524    itim_sup=-1
525    ! return to main program (with value=missing_value)
526    return
527  else ! general case
528    do i=1,timelen-1
529      if (time(i).le.sol) then
530        itim_inf=i
531      else
532        exit
533      endif
534    enddo
535    itim_sup=itim_inf+1
536  endif ! of if ((sol.lt.time(1)).or.(sol.gt.time(timenlen)))
537endif ! of if (sol.ne.prev_sol)
538!write(*,*) 'itim_inf=',itim_inf," time(itim_inf)=",time(itim_inf)
539!write(*,*) 'itim_sup=',itim_sup," time(itim_sup)=",time(itim_sup)
540
541! 2. Interpolate
542! check that there are no "missing_value" in the field() elements we need
543! otherwise return to main program (with value=missing_value)
544if (field(ilon_inf,ilat_inf,ialt_inf,itim_inf).eq.missing_value) return
545if (field(ilon_inf,ilat_inf,ialt_inf,itim_sup).eq.missing_value) return
546if (field(ilon_inf,ilat_inf,ialt_sup,itim_inf).eq.missing_value) return
547if (field(ilon_inf,ilat_inf,ialt_sup,itim_sup).eq.missing_value) return
548if (field(ilon_inf,ilat_sup,ialt_inf,itim_inf).eq.missing_value) return
549if (field(ilon_inf,ilat_sup,ialt_inf,itim_sup).eq.missing_value) return
550if (field(ilon_inf,ilat_sup,ialt_sup,itim_inf).eq.missing_value) return
551if (field(ilon_inf,ilat_sup,ialt_sup,itim_sup).eq.missing_value) return
552if (field(ilon_sup,ilat_inf,ialt_inf,itim_inf).eq.missing_value) return
553if (field(ilon_sup,ilat_inf,ialt_inf,itim_sup).eq.missing_value) return
554if (field(ilon_sup,ilat_inf,ialt_sup,itim_inf).eq.missing_value) return
555if (field(ilon_sup,ilat_inf,ialt_sup,itim_sup).eq.missing_value) return
556if (field(ilon_sup,ilat_sup,ialt_inf,itim_inf).eq.missing_value) return
557if (field(ilon_sup,ilat_sup,ialt_inf,itim_sup).eq.missing_value) return
558if (field(ilon_sup,ilat_sup,ialt_sup,itim_inf).eq.missing_value) return
559if (field(ilon_sup,ilat_sup,ialt_sup,itim_sup).eq.missing_value) return
560
561! 2.1 Linear interpolation in time
562coeff=(sol-time(itim_inf))/(time(itim_sup)-time(itim_inf))
563t_interp(1,1,1)=field(ilon_inf,ilat_inf,ialt_inf,itim_inf)+ &
564                coeff*(field(ilon_inf,ilat_inf,ialt_inf,itim_sup)- &
565                       field(ilon_inf,ilat_inf,ialt_inf,itim_inf))
566t_interp(1,1,2)=field(ilon_inf,ilat_inf,ialt_sup,itim_inf)+ &
567                coeff*(field(ilon_inf,ilat_inf,ialt_sup,itim_sup)- &
568                       field(ilon_inf,ilat_inf,ialt_sup,itim_inf))
569t_interp(1,2,1)=field(ilon_inf,ilat_sup,ialt_inf,itim_inf)+ &
570                coeff*(field(ilon_inf,ilat_sup,ialt_inf,itim_sup)- &
571                       field(ilon_inf,ilat_sup,ialt_inf,itim_inf))
572t_interp(1,2,2)=field(ilon_inf,ilat_sup,ialt_sup,itim_inf)+ &
573                coeff*(field(ilon_inf,ilat_sup,ialt_sup,itim_sup)- &
574                       field(ilon_inf,ilat_sup,ialt_sup,itim_inf))
575t_interp(2,1,1)=field(ilon_sup,ilat_inf,ialt_inf,itim_inf)+ &
576                coeff*(field(ilon_sup,ilat_inf,ialt_inf,itim_sup)- &
577                       field(ilon_sup,ilat_inf,ialt_inf,itim_inf))
578t_interp(2,1,2)=field(ilon_sup,ilat_inf,ialt_sup,itim_inf)+ &
579                coeff*(field(ilon_sup,ilat_inf,ialt_sup,itim_sup)- &
580                       field(ilon_sup,ilat_inf,ialt_sup,itim_inf))
581t_interp(2,2,1)=field(ilon_sup,ilat_sup,ialt_inf,itim_inf)+ &
582                coeff*(field(ilon_sup,ilat_sup,ialt_inf,itim_sup)- &
583                       field(ilon_sup,ilat_sup,ialt_inf,itim_inf))
584t_interp(2,2,2)=field(ilon_sup,ilat_sup,ialt_sup,itim_inf)+ &
585                coeff*(field(ilon_sup,ilat_sup,ialt_sup,itim_sup)- &
586                       field(ilon_sup,ilat_sup,ialt_sup,itim_inf))
587
588! 2.2 Vertical interpolation
589if (((varname=='rho').or.(varname=='pressure')).and.(alttype=='z')) then
590  ! do the interpolation on the log of the quantity
591  coeff=(alt-altitude(ialt_inf))/(altitude(ialt_sup)-altitude(ialt_inf))
592  zt_interp(1,1)=log(t_interp(1,1,1))+coeff* &
593                             (log(t_interp(1,1,2))-log(t_interp(1,1,1)))
594  zt_interp(1,2)=log(t_interp(1,2,1))+coeff* &
595                             (log(t_interp(1,2,2))-log(t_interp(1,2,1)))
596  zt_interp(2,1)=log(t_interp(2,1,1))+coeff* &
597                             (log(t_interp(2,1,2))-log(t_interp(2,1,1)))
598  zt_interp(2,2)=log(t_interp(2,2,1))+coeff* &
599                             (log(t_interp(2,2,2))-log(t_interp(2,2,1)))
600  zt_interp(1:2,1:2)=exp(zt_interp(1:2,1:2))
601else ! general case
602  coeff=(alt-altitude(ialt_inf))/(altitude(ialt_sup)-altitude(ialt_inf))
603  zt_interp(1,1)=t_interp(1,1,1)+coeff*(t_interp(1,1,2)-t_interp(1,1,1))
604  zt_interp(1,2)=t_interp(1,2,1)+coeff*(t_interp(1,2,2)-t_interp(1,2,1))
605  zt_interp(2,1)=t_interp(2,1,1)+coeff*(t_interp(2,1,2)-t_interp(2,1,1))
606  zt_interp(2,2)=t_interp(2,2,1)+coeff*(t_interp(2,2,2)-t_interp(2,2,1))
607endif
608
609! 2.3 Latitudinal interpolation
610coeff=(lat-latitude(ilat_inf))/(latitude(ilat_sup)-latitude(ilat_inf))
611yzt_interp(1)=zt_interp(1,1)+coeff*(zt_interp(1,2)-zt_interp(1,1))
612yzt_interp(2)=zt_interp(2,1)+coeff*(zt_interp(2,2)-zt_interp(2,1))
613
614! 2.4 longitudinal interpolation
615coeff=(lon-longitude(ilon_inf))/(longitude(ilon_sup)-longitude(ilon_inf))
616value=yzt_interp(1)+coeff*(yzt_interp(2)-yzt_interp(1))
617
618end subroutine extraction
619
620!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
621subroutine ls2sol(ls,sol)
622
623implicit none
624!  Arguments:
625real,intent(in) :: ls
626real,intent(out) :: sol
627
628!  Local:
629double precision xref,zx0,zteta,zz
630!xref: mean anomaly, zteta: true anomaly, zx0: eccentric anomaly
631double precision year_day
632double precision peri_day,timeperi,e_elips
633double precision pi,degrad
634parameter (year_day=668.6d0) ! number of sols in a martian year
635parameter (peri_day=485.35d0) ! date (in sols) of perihelion
636!  timeperi: 2*pi*( 1 - Ls(perihelion)/ 360 ); Ls(perihelion)=250.99
637parameter (timeperi=1.90258341759902d0)
638parameter (e_elips=0.0934d0)  ! eccentricity of orbit
639parameter (pi=3.14159265358979d0)
640parameter (degrad=57.2957795130823d0)
641
642      if (abs(ls).lt.1.0e-5) then
643         if (ls.ge.0.0) then
644            sol = 0.0
645         else
646            sol = real(year_day)
647         end if
648         return
649      end if
650
651      zteta = ls/degrad + timeperi
652      zx0 = 2.0*datan(dtan(0.5*zteta)/dsqrt((1.+e_elips)/(1.-e_elips)))
653      xref = zx0-e_elips*dsin(zx0)
654      zz = xref/(2.*pi)
655      sol = real(zz*year_day + peri_day)
656      if (sol.lt.0.0) sol = sol + real(year_day)
657      if (sol.ge.year_day) sol = sol - real(year_day)
658
659
660end subroutine ls2sol
661
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