Tides
=====

**Related CPP options:**

=================== ============================================================
TIDES               Activate tidal forcing at open boundaries
SSH_TIDES           Process and use tidal sea level data
UV_TIDES            Process and use tidal current data
OBC_REDUCED_PHYSICS | Compute tidal velcocity from tidal elevation 
                    | in case of tidal current is not available
TIDERAMP            | Apply ramping on tidal forcing (1 day) at initialization
                    | Warning! This should be undefined if restarting the model
TIDES_MAS           | Harmonic composition to build tide elevation  
                    | from SHOM (Simon method) to take into account nodal correction
                    | Harmonic composition for currents use the classic method
                    | if UV_TIDES is activated.    
=================== ============================================================

*Preselected options:*
::

# ifdef TIDES 
#  define SSH_TIDES 
#  define UV_TIDES 
#  ifndef UV_TIDES
#   define OBC_REDUCED_PHYSICS
#  endif
#  define TIDERAMP 
# endif

*Coastal case options with TIDES_MAS:*
::
    
# ifdef TIDES 
#  define SSH_TIDES 
#  define UV_TIDES 
#  ifndef UV_TIDES
#   define OBC_REDUCED_PHYSICS
#  endif
#  define TIDES_MAS 
#  define TIDERAMP 
# endif

.. important ::

    With **TIDES_MAS** the user only need an atlas with tidal harmonics (elevation and current) 
    interpolated on the Croco grid. The harmonics dont need to take nodal correction in their amplitude and
    phase like in classic method.

.. important ::

    **TIDES_MAS** requires the **USE_CALENDAR** cppkey, because it needs a precise time reference and the origin
    date from the harmonic's atlas must be 1900-01-01.