! source file: /sfs/fs1/work-geomar6/smomw113/UVic_ESCM/2.9_dk_0814/updates/07_aouassim/source/common/co2data.F
      subroutine co2emitdata

      return
      end

      subroutine co2ccndata

      return
      end

      subroutine satdata

      return
      end

      subroutine co2ccnforcdata

!=======================================================================
!     routine to read and interpolate one dimensional forcing data
!=======================================================================
! ! I will use this file only to develop the subroutine co2ccnforcdata.
! Later this code shall be moved into the file co2data.F.
!
! wkoeve@geomar.de,  7.09.15
!
! In order to keep this as simple as possible, I will not consider co-operability
! with several other options, namely
! O_carbon_co2_2d, O_co2emit_track_co2, defined O_co2emit_track_sat
!
! I need to add a respective break statement early in this routine, or in UVic_ESCM,
! to make sure there is no conflict with these options. See lines 698ff for a similar example.
!
! As I have coded it right now, one should set both 1 and 1.
! If only 1 is set the value of co2_yr (=pyear) will be used continuously.
!
! In this version, I have changed variable name to fit the std of UVic better.
!

      implicit none

      character(120) :: fname, name, new_file_name, text

      integer iou, n, ln, ib(10), ic(10)

      logical inqvardef, exists, track

      real avg_co2, dat(3), data_time, pk, tim(3), wt1, wt3, fa

      real, allocatable :: data(:), time(:)

      save dat, data, ln, tim, time

      include "size.h"
      include "param.h"
      include "pconst.h"
      include "stdunits.h"
      include "calendar.h"
      include "cembm.h"
      include "switch.h"
      include "tmngr.h"
      include "atm.h"

! WK: The following block is for the call from *subroutine setembm*, I think.
      if (.not. allocated (time)) then
        print*, "####################################################"
        print*, "WK: loading data from A_co2_forc.nc for forced mode."
        name = "A_co2_forc.nc"
        fname = new_file_name (name)
	       print*,"load from the following file: ",trim(fname)
        inquire (file=trim(fname), exist=exists)
        if (.not. exists) then
          print*, "==> Error: ", trim(fname), " does not exist."
          stop '=>co2ccnforc'
        else
          call openfile (fname, iou)
          call getdimlen ('time', iou, ln)
          allocate ( time(ln) )
          allocate ( data(ln) )
          ib(:) = 1
          ic(:) = ln
          call getvara ('time', iou, ln, ib, ic, time, c1, c0)
          text = 'years'
          call getatttext (iou, 'time', 'units', text)
          if (trim(text) .eq. "days since 1-1-1")
     &      time(:) = time(:)/yrlen - 1.
          if (trim(text) .eq. "days since 0-1-1")
     &       time(:) = time(:)/yrlen
          if (trim(text) .eq. "years since 1-1-1")
     &      time(:) = time(:) - 1.
          exists = inqvardef('A_co2forc', iou)
          if (.not. exists) then
            print*, "==>  Warning: A_co2forc data does not exist."
          else
            call getvara ('A_co2forc', iou, ln, ib, ic, data, c1, c0)
          endif
         endif
        tim(:) = time(1)
        dat(:) = data(1)
      endif

! WK: Here the interpolation starts at any call of this routine from *subroutine gasbc*
! WK: Initially, co2_yr = pyear by default.

      data_time = year0 + accel_yr0 + (relyr - accel_yr0)*accel
      tim(2) = min(time(ln), max(time(1), data_time))

      if (tim(2) .le. time(1)) then
        dat(2) = data(1)
      elseif (tim(2) .ge. time(ln)) then
        dat(2) = data(ln)
      else
        if (tim(2) .gt. tim(3)) then
          do n=2,ln
            if (time(n-1) .le. tim(2) .and. time(n) .ge. tim(2)) then
              tim(1) = time(n-1)
              dat(1) = data(n-1)
              tim(3) = time(n)
              dat(3) = data(n)
            endif
          enddo
        endif
        wt1 = 1.
        if (tim(3) .ne. tim(1)) wt1 = (tim(3)-tim(2))/(tim(3)-tim(1))
        wt1 = max(0., min(1., wt1))
        wt3 = 1. - wt1
        dat(2) = dat(1)*wt1 + dat(3)*wt3
      endif

      co2ccnforc = dat(2)
      if (tsits) then
         print*,"co2ccnforc: ",co2ccnforc
      endif

      return
      end