source: trunk/LMDZ.GENERIC/libf/phystd/setspi.F90 @ 2987

Last change on this file since 2987 was 2668, checked in by aslmd, 3 years ago

Fixed floating overflow that could occur in setspi.F90

File size: 7.5 KB
Line 
1      subroutine setspi
2
3!==================================================================
4!     
5!     Purpose
6!     -------
7!     Set up spectral intervals and Planck function in the longwave.
8!     
9!     Authors
10!     -------
11!     Adapted from setspi in the NASA Ames radiative code by
12!     Robin Wordsworth (2009).
13!     
14!     Called by
15!     ---------
16!     callcorrk.F
17!     
18!     Calls
19!     -----
20!     none
21!     
22!==================================================================
23
24      use radinc_h,    only: L_NSPECTI,corrkdir,banddir,NTstart,NTstop,NTfac
25      use radcommon_h, only: BWNI,BLAMI,WNOI,DWNI,WAVEI,planckir,sigma
26      use datafile_mod, only: datadir
27      use comcstfi_mod, only: pi
28
29      implicit none
30
31      logical file_ok
32      integer nw, nt, m, mm, file_entries
33      real*8 a, b, ans, y, bpa, bma, T, dummy
34
35      character(len=30)  :: temp1
36      character(len=200) :: file_id
37      character(len=200) :: file_path
38
39!     C1 and C2 values from Goody and Yung (2nd edition)  MKS units
40!     These values lead to a "sigma" (sigma*T^4) of 5.67032E-8 W m^-2 K^-4
41
42      real*8 :: c1 = 3.741832D-16 ! W m^-2
43      real*8 :: c2 = 1.438786D-2  ! m K
44     
45      real*8 :: lastband(2), plancksum
46
47      !! used to count lines
48      integer :: nb
49      integer :: ierr
50
51      logical forceEC, planckcheck
52
53      real*8 :: x(12) = [ -0.981560634246719D0,  -0.904117256370475D0, &
54      -0.769902674194305D0,  -0.587317954286617D0,                     &
55      -0.367831498998180D0,  -0.125233408511469D0,                     &
56       0.125233408511469D0,   0.367831498998180D0,                     &
57       0.587317954286617D0,   0.769902674194305D0,                     &
58       0.904117256370475D0,   0.981560634246719D0  ]
59
60      real*8 :: w(12) = [  0.047175336386512D0,   0.106939325995318D0, &
61           0.160078328543346D0,   0.203167426723066D0,                 &
62           0.233492536538355D0,   0.249147045813403D0,                 &
63           0.249147045813403D0,   0.233492536538355D0,                 &
64           0.203167426723066D0,   0.160078328543346D0,                 &
65           0.106939325995318D0,   0.047175336386512D0  ]
66      mm=0
67
68      forceEC=.true.
69      planckcheck=.true.
70
71!=======================================================================
72!     Set up spectral bands - wavenumber [cm^(-1)]. Go from smaller to
73!     larger wavenumbers.
74
75      write(temp1,'(i2.2)') L_NSPECTI
76      !file_id='/corrk_data/' // corrkdir(1:LEN_TRIM(corrkdir)) // '/narrowbands_IR.in'
77      file_id='/corrk_data/'//trim(adjustl(banddir))//'/narrowbands_IR.in'
78      file_path=TRIM(datadir)//TRIM(file_id)
79
80      ! check that the file exists
81      inquire(FILE=file_path,EXIST=file_ok)
82      if(.not.file_ok) then
83         write(*,*)'The file ',TRIM(file_path)
84         write(*,*)'was not found by setspi.F90, exiting.'
85         write(*,*)'Check that your path to datagcm:',trim(datadir)
86         write(*,*)' is correct. You can change it in callphys.def with:'
87         write(*,*)' datadir = /absolute/path/to/datagcm'
88         write(*,*)'Also check that the corrkdir you chose in callphys.def exists.'
89         call abort
90      endif
91   
92!$OMP MASTER   
93      nb=0
94      ierr=0
95      ! check that the file contains the right number of bands
96      open(131,file=file_path,form='formatted')
97      read(131,*,iostat=ierr) file_entries
98      do while (ierr==0)
99        read(131,*,iostat=ierr) dummy
100!        write(*,*) 'setspi: file_entries:',dummy,'ierr=',ierr
101        if (ierr==0) nb=nb+1
102      enddo
103      close(131)
104
105      write(*,*) 'setspi: L_NSPECTI = ',L_NSPECTI, 'in the model '
106      write(*,*) '        there are   ',nb, 'entries in ',TRIM(file_path)
107      if(nb.ne.L_NSPECTI) then
108         write(*,*) 'MISMATCH !! I stop here'
109         call abort
110      endif
111
112      ! load and display the data
113      open(111,file=file_path,form='formatted')
114      read(111,*)
115      do M=1,L_NSPECTI-1
116         read(111,*) BWNI(M)
117      end do
118      read(111,*) lastband
119      close(111)
120      BWNI(L_NSPECTI)  =lastband(1)
121      BWNI(L_NSPECTI+1)=lastband(2)
122!$OMP END MASTER
123!$OMP BARRIER
124
125      print*,''
126      print*,'setspi: IR band limits:'
127      do M=1,L_NSPECTI+1
128         print*,m,'-->',BWNI(M),' cm^-1'
129      end do
130
131!     Set up mean wavenumbers and wavenumber deltas.  Units of
132!     wavenumbers is cm^(-1); units of wavelengths is microns.
133
134      do M=1,L_NSPECTI
135         WNOI(M)  = 0.5D0*(BWNI(M+1)+BWNI(M))
136         DWNI(M)  = BWNI(M+1)-BWNI(M)
137         WAVEI(M) = 1.0D+4/WNOI(M)
138         BLAMI(M) = 0.01D0/BWNI(M)         
139      end do
140      BLAMI(M) = 0.01D0/BWNI(M)
141!     note M=L_NSPECTI+1 after loop due to Fortran bizarreness
142
143!=======================================================================
144!     For each IR wavelength interval, compute the integral of B(T), the
145!     Planck function, divided by the wavelength interval, in cm-1.  The
146!     integration is in MKS units, the final answer is the same as the
147!     original planck.f; W m^-2 wavenumber^-1, where wavenumber is in CM^-1.
148
149      print*,''
150      print*,'setspi: Current Planck integration range:'
151      print*,'T = ',dble(NTstart)/NTfac, ' to ',dble(NTstop)/NTfac,' K.'
152
153      IF(.NOT.ALLOCATED(planckir)) ALLOCATE(planckir(L_NSPECTI,NTstop-NTstart+1))
154
155      do NW=1,L_NSPECTI
156         a = 1.0D-2/BWNI(NW+1)
157         b = 1.0D-2/BWNI(NW)
158         bpa = (b+a)/2.0D0
159         bma = (b-a)/2.0D0
160         ! if (nw .eq. 25) then !LT debug
161         !    print*, "a = ",a
162         !    print*, "b= ",b
163         !    print*,"bpa = ",bpa
164         !    print*, "bma = ",bma
165         ! endif
166         do nt=NTstart,NTstop
167            T   = dble(NT)/NTfac
168            ans = 0.0D0
169            do mm=1,12
170               y    = bma*x(mm)+bpa
171               !to avoid floating overflow when T is low and optical wavelength
172               if ((c2/(y*T)) .lt. 700.0D0) then
173                  ans  = ans + w(mm)*c1/(y**5*(exp(c2/(y*T))-1.0D0))
174               else
175                  ans = ans +0.0D0
176               endif
177            end do
178            planckir(NW,nt-NTstart+1) = ans*bma/(PI*DWNI(NW))
179         end do
180      end do
181         
182      ! force planck=sigma*eps*T^4 for each temperature in array
183      if(forceEC)then
184         print*,'setspi: Force F=sigma*eps*T^4 for all values of T!'
185         do nt=NTstart,NTstop
186            plancksum=0.0D0
187            T=dble(NT)/NTfac
188       
189            do NW=1,L_NSPECTI
190               plancksum=plancksum+  &
191                  planckir(NW,nt-NTstart+1)*DWNI(NW)*pi
192            end do
193
194            do NW=1,L_NSPECTI
195               planckir(NW,nt-NTstart+1)=     &
196                  planckir(NW,nt-NTstart+1)*  &
197                          sigma*(dble(nt)/NTfac)**4/plancksum
198            end do
199         end do
200      endif
201
202      if(planckcheck)then
203         ! check energy conservation at lower temperature boundary
204         plancksum=0.0D0
205         nt=NTstart
206         do NW=1,L_NSPECTI
207            plancksum=plancksum+planckir(NW,nt-NTstart+1)*DWNI(NW)*pi
208         end do
209         print*,'setspi: At lower limit:'
210         print*,'in model sig*T^4 = ',plancksum,' W m^-2'
211         print*,'actual sig*T^4   = ',sigma*(dble(nt)/NTfac)**4,' W m^-2'
212         
213         ! check energy conservation at upper temperature boundary
214         plancksum=0.0D0
215         nt=NTstop
216         do NW=1,L_NSPECTI
217            plancksum=plancksum+planckir(NW,nt-NTstart+1)*DWNI(NW)*pi
218         end do
219         print*,'setspi: At upper limit:'
220         print*,'in model sig*T^4 = ',plancksum,' W m^-2'
221         print*,'actual sig*T^4   = ',sigma*(dble(nt)/NTfac)**4,' W m^-2'
222         print*,''
223      endif
224
225      return
226    end subroutine setspi
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