FlorianDeconinck
commented
1 month ago Use case in UW
subroutine conden(p,thl,qt,th,qv,ql,qi,rvls,id_check)
implicit none
real, intent(in) :: p
real, intent(in) :: thl
real, intent(in) :: qt
real, intent(out) :: th
real, intent(out) :: qv
real, intent(out) :: ql
real, intent(out) :: qi
real, intent(out) :: rvls
integer, intent(out) :: id_check
! Local
real*8 :: tc
real :: temps,ps
real*8 :: leff,nu,qc
integer :: iteration
real*8 :: qs ! Saturation specific humidity
tc = thl*exnerfn(p)
! nu = max(min((258._r8-tc)/20._r8,1.0_r8),0.0_r8) ! ice fraction of condensate
nu = ICE_FRACTION(real(tc),0.0,0.0)
leff = (1._r8- nu)*xlv + nu*xls ! effective latent heat
temps = tc
ps = p
qs = GEOS_QSAT(temps, ps/100.)
rvls = qs
if ( qs .ge. qt ) then ! no condensation
id_check = 0
qv = qt
qc = 0.
ql = 0.
qi = 0.
th = thl !tc/exnerfn(p)
else ! condensation
do iteration = 1,10
temps = temps + ( (tc-temps)*cp/leff + qt - rvls )/( cp/leff + ep2*leff*rvls/(r*temps*temps) )
qs = GEOS_QSAT(temps, ps/100.)
rvls = qs
end do
qc = max( qt-qs, 0._r8 )
qv = qt - qc
ql = qc*(1._r8 - nu)
qi = nu*qc
th = temps/exnerfn(p)
if ( abs((temps-(leff/cp)*qc)-tc) .ge. 1._r8 ) then
id_check = 1
else
id_check = 0
end if
end if
return
end subroutine conden
The Aer Activation port shows the usage of 64-bit literals in an otherwise 32-bit code
Until now we were operating under the assumption of a fully 32-bit or fully 64-bit precision calculation, with the exception of the occasional upcasting of a Field to keep precision up.
With this finding, we are back to the drawing board.
Fortran uses a "variable precision is the precision of the operation" technique to define ops precision between literals and variables. We could try to replicate this in GT4Py/DaCe to force "best precision" on single ops.
Another option is to work at NDSL level and have an override on a particular stencil to be at 64-bit, if GT4Py/DaCe allows for it.
Parent: https://github.com/GEOS-ESM/SMT-Nebulae/issues/36