I have been trying to reproduce a result from an older version of ROMS (version 92) using a newer version (version 526). The simulation is pretty simple in that it only has tidal forcing with the M2 consituent and has constant T (20C) and S (35 PSU) initial conditions. There is no river, met/atmos or open boundary non-tidal/T/S forcing. So the only things which evolve are water levels and currents and T and S remain fixed. However, the two ROMS versions give different results and I have not been able to reconcile them until I began to look at the code and I found the following :
ROMS version 92 :
# elif defined SOUTH_M2FLATHER
!
! Southern edge, Flather boundary condition.
!
DO i=Istr,Iend
# if !defined SSH_TIDES && !defined UV_TIDES
# ifdef FSOBC_REDUCED
bry_pgr=-g*(zeta(i,Jstr,know)- &
& BOUNDARY(ng)%zeta_south(i))* &
& 0.5_r8*GRID(ng)%pn(i,Jstr)
# else
ROMS version 526:
# elif defined SOUTH_M2FLATHER
!
! Southern edge, Flather boundary condition.
!
DO i=Istr,Iend
# if defined SSH_TIDES && !defined UV_TIDES
# ifdef FSOBC_REDUCED
bry_pgr=-g*(zeta(i,Jstr,know)- &
& BOUNDARY(ng)%zeta_south(i))* &
& 0.5_r8*GRID(ng)%pn(i,Jstr)
#else
As you can see, one has "defined SSH_TIDES" and the other has "!defined SSH_TIDES".
Is this a bug? Which version is correct?