Open Boundary Conditions

[luis.chetu.83]

Hi, I wanna run ROMS model for my own aplication, my studio area is semi-closed and the open boundary is located on southern, could I apply a M2 tide period like an initial condition?

I hope your answer soon

Cheers

Luis

[kate]

There are a couple of choices for applying tidal boundary conditions:

1. If it's analytic, one constituent, apply consistent functions for the zeta and M2 boundary conditions. The velocity and surface elevation are out of phase with each other.

2. If it's a realistic domain, extract the constituent(s) from a tidal model and apply them to the model as a ROMS tidal forcing file. Note that ROMS wants to read the whole 2D grid, though it only uses the boundaries.

3. Provide the tides as a boundary condition file at sufficient temporal resolution.

Notes:

1. For any of these, if you only provide the zeta values, try M2REDUCED to ask the model to figure out sensible velocity conditions to go with it.

2. If you want to do an actual tidal prediction, you need to include the effects of the long-period tides in addition to the eight regular diurnal and semi-diurnal constituents. Some people find this easier to do through a time-dependent boundary condition, though my icy ROMS branch has a stab at getting those corrections in when using the ROMS tidal forcing file.

[luis.chetu.83]

Thanks a lot for your reply Kate!!

I`m going to take into account your comments for my aplication.

Cheers

Luis

[matias.dinapoli]

Hi! I'm interested at the 3° option, but I don't see how putting a temporal serie of "zeta" in the boundary netcdf file. I choosed this option because I want to see how evolve the tide on my coast.

[kate]

Tools exist for creating boundary files. Is there some particular language you are looking to do this in? Is this analytic or realistic?

[matias.dinapoli]

I want to do it with realistics information. I work with FES2004 to get data of a global model to force my regional model, so I should have a boundary file with a temporal series of the surface elevation for each edge.

[kate]

You need to create a boundary file with a record at least every three hours. Do you have a source of this field? Again, what kind of help are you looking for? Ideas or code?

[matias.dinapoli]

I have the tidal forcing files created from frc_tides.cdl for each boundary of my domain (just amplitude and phase of 14 harmonics extracted from FES2004). And now I want to force only the boundaries. My question is: how must I indicate to ROMS that it use frc_tide_south.nc to force the south open boundary, and so on? Because I don't know if I have to activate SSH_TIDES, ADD_FSOBC or indicate something more. I'm really confused.