boundary.F90

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!+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
!
!  Subroutine :  b o u n d a r y
!
!> @file
!!
!! Computation of the surface temperature (must be less than 0 deg C!)
!! and of the accumulation-ablation function.
!!
!! @section Copyright
!!
!! Copyright 2009-2013 Ralf Greve
!!
!! @section License
!!
!! This file is part of SICOPOLIS.
!!
!! SICOPOLIS is free software: you can redistribute it and/or modify
!! it under the terms of the GNU General Public License as published by
!! the Free Software Foundation, either version 3 of the License, or
!! (at your option) any later version.
!!
!! SICOPOLIS is distributed in the hope that it will be useful,
!! but WITHOUT ANY WARRANTY; without even the implied warranty of
!! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
!! GNU General Public License for more details.
!!
!! You should have received a copy of the GNU General Public License
!! along with SICOPOLIS.  If not, see <http://www.gnu.org/licenses/>.
!<
!+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

!-------------------------------------------------------------------------------
!> Computation of the surface temperature (must be less than 0 deg C!)
!! and of the accumulation-ablation function.
!<------------------------------------------------------------------------------
subroutine boundary(time, dtime, dxi, deta, &
                    delta_ts, glac_index, z_sl, dzsl_dtau, z_mar)

use sico_types
use sico_variables

implicit none

real(dp), intent(in) :: time, dtime, dxi, deta

real(dp), intent(out)   :: delta_ts, glac_index, dzsl_dtau, z_mar
real(dp), intent(inout) :: z_sl

! Further return variables
! (defined as global variables in module sico_variables):
!
!    accum(j,i), as_perp(j,i), temp_s(j,i)

integer(i2b) :: mask_update
integer(i4b) :: i, j
integer(i4b) :: i_gr, i_kl
real(dp) :: z_sl_old
real(dp) :: z_sl_min, t1, t2, t3, t4, t5, t6
real(dp) :: time_gr, time_kl
real(dp), dimension(0:JMAX,0:IMAX) :: dist
logical, dimension(0:JMAX,0:IMAX) :: check_point

!-------- Initialization of intent(out) variables --------

z_sl_old   = z_sl

delta_ts   = 0.0_dp
glac_index = 0.0_dp
z_sl       = 0.0_dp
dzsl_dtau  = 0.0_dp
z_mar      = 0.0_dp

!-------- Surface-temperature deviation from present values --------

#if TSURFACE==1
delta_ts = delta_ts0
!                           ! Steady state with prescribed constant
!                           ! air-temperature deviation
#elif TSURFACE==3
delta_ts = sine_amplit &
           *cos(2.0_dp*pi*time/(sine_period*year_sec)) &
           -sine_amplit
!                           ! Sinusoidal air-temperature forcing
#elif TSURFACE==4

!  ------ delta_ts from the GRIP record

if (time/year_sec.lt.real(grip_time_min,dp)) then
   delta_ts = griptemp(0)
else if (time/year_sec.lt.real(grip_time_max,dp)) then

   i_kl = floor(((time/year_sec) &
          -real(grip_time_min,dp))/real(grip_time_stp,dp))
   i_kl = max(i_kl, 0)

   i_gr = ceiling(((time/year_sec) &
          -real(grip_time_min,dp))/real(grip_time_stp,dp))
   i_gr = min(i_gr, ndata_grip)

   if (i_kl.eq.i_gr) then

      delta_ts = griptemp(i_kl)

   else

      time_kl = (grip_time_min + i_kl*grip_time_stp) *year_sec
      time_gr = (grip_time_min + i_gr*grip_time_stp) *year_sec

      delta_ts = griptemp(i_kl) &
                +(griptemp(i_gr)-griptemp(i_kl)) &
                *(time-time_kl)/(time_gr-time_kl)
                 ! linear interpolation of the ice-core data

   end if

else
   delta_ts  = griptemp(ndata_grip)
end if

delta_ts = delta_ts * grip_temp_fact
!                ! modification by constant factor

#elif TSURFACE==5
!     Enter here delta_ts scenario:

#endif

!-------- Sea level --------

#if SEA_LEVEL==1
!  ------ constant sea level
z_sl = z_sl0

#elif SEA_LEVEL==2
!  ------ saw-tooth-shaped palaeoclimatic sea-level forcing

z_sl_min = -130.0_dp

t1 = -250000.0_dp *year_sec
t2 = -140000.0_dp *year_sec
t3 = -125000.0_dp *year_sec
t4 =  -21000.0_dp *year_sec
t5 =   -8000.0_dp *year_sec
t6 =       0.0_dp *year_sec

if (time.lt.t1) then
   z_sl = 0.0_dp
else if (time.lt.t2) then
   z_sl = z_sl_min*(time-t1)/(t2-t1)
else if (time.lt.t3) then
   z_sl = -z_sl_min*(time-t3)/(t3-t2)
else if (time.lt.t4) then
   z_sl = z_sl_min*(time-t3)/(t4-t3)
else if (time.lt.t5) then
   z_sl = -z_sl_min*(time-t5)/(t5-t4)
else if (time.lt.t6) then
   z_sl = 0.0_dp
else
   z_sl = 0.0_dp
end if

#elif SEA_LEVEL==3

!  ------ z_sl from the SPECMAP record

if (time/year_sec.lt.real(specmap_time_min,dp)) then
   z_sl = specmap_zsl(0)
else if (time/year_sec.lt.real(specmap_time_max,dp)) then

   i_kl = floor(((time/year_sec) &
          -real(specmap_time_min,dp))/real(specmap_time_stp,dp))
   i_kl = max(i_kl, 0)

   i_gr = ceiling(((time/year_sec) &
          -real(specmap_time_min,dp))/real(specmap_time_stp,dp))
   i_gr = min(i_gr, ndata_specmap)

   if (i_kl.eq.i_gr) then

      z_sl = specmap_zsl(i_kl)

   else

      time_kl = (specmap_time_min + i_kl*specmap_time_stp) *year_sec
      time_gr = (specmap_time_min + i_gr*specmap_time_stp) *year_sec

      z_sl = specmap_zsl(i_kl) &
                +(specmap_zsl(i_gr)-specmap_zsl(i_kl)) &
                *(time-time_kl)/(time_gr-time_kl)
                 ! linear interpolation of the sea-level data

   end if

else
   z_sl  = specmap_zsl(ndata_specmap)
end if

#endif

!  ------ Time derivative of the sea level

if ( z_sl_old > -999999.9_dp ) then
   dzsl_dtau = (z_sl-z_sl_old)/dtime
else   ! only dummy value for z_sl_old available
   dzsl_dtau = 0.0_dp
end if

!  ------ Minimum bedrock elevation for extent of marine ice

#if MARGIN==2

#if ( MARINE_ICE_CALVING==2 || MARINE_ICE_CALVING==3 )
z_mar = z_mar
#elif ( MARINE_ICE_CALVING==4 || MARINE_ICE_CALVING==5 )
z_mar = fact_z_mar*z_sl
#elif ( MARINE_ICE_CALVING==6 || MARINE_ICE_CALVING==7 )
if (z_sl >= -80.0_dp) then
   z_mar = 2.5_dp*z_sl
else
   z_mar = 10.25_dp*(z_sl+80.0_dp)-200.0_dp
end if
z_mar = fact_z_mar*z_mar
#endif

#endif

!  ------ Update of the mask according to the sea level

!    ---- Check all sea and floating-ice points and their direct
!         neighbours

do i=0, imax
do j=0, jmax
   check_point(j,i) = .false.
end do
end do

do i=1, imax-1
do j=1, jmax-1
   if (maske(j,i).ge.2) then
      check_point(j  ,i  ) = .true.
      check_point(j  ,i+1) = .true.
      check_point(j  ,i-1) = .true.
      check_point(j+1,i  ) = .true.
      check_point(j-1,i  ) = .true.
   end if
end do
end do

do i=1, imax-1
do j=1, jmax-1
   if (check_point(j,i)) then
      maske_neu(j,i) = mask_update(z_sl, i, j)
   end if
end do
end do

!    ---- Assign new values of the mask

do i=1, imax-1
do j=1, jmax-1
   if (check_point(j,i)) then
      maske(j,i) = maske_neu(j,i)
   end if
end do
end do

!-------- Surface air temperature and accumulation-ablation function --------

do i=0, imax
do j=0, jmax
   dist(j,i) = sqrt( (xi(i)-x_hat)**2 + (eta(j)-y_hat)**2 )
end do
end do

do i=0, imax
do j=0, jmax

   temp_s(j,i) = temp_min + s_t*dist(j,i)
   temp_s(j,i) = temp_s(j,i) + delta_ts
                 ! Correction with temperature deviation delta_ts
   if (temp_s(j,i).gt. -0.001_dp) temp_s(j,i) = -0.001_dp
                               ! Cut-off of positive air temperatures

   accum_present(j,i) = b_max
   accum(j,i)         = accum_present(j,i)

   as_perp(j,i) = s_b*(eld-dist(j,i))
   if (as_perp(j,i).gt.accum(j,i)) as_perp(j,i) = accum(j,i)

end do
end do

end subroutine boundary
!