Open boundary CPP option for river?

General scientific issues regarding ROMS

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pengjia
Posts: 10
Joined: Thu Aug 21, 2008 4:24 pm
Location: UMCP

Open boundary CPP option for river?

#1 Unread post by pengjia »

Hi all,

I couldn't find any boundary CPP for river. I think we need some kind of open boundary conditions like free surface conditions if we cut one river not at its head, for example in river plume applications. Tide can reach the source point along the river channel and cause water level fluctuation, but we know there should not be sea-land boundary and tide should go straight on not getting relected there.

Another silly question about how ROMS calculates zeta at the first water-RHO point close to the source.
The point sources are added at the U/V point not the RHO point. So elevation at the first RHO point in the river channel can be calculated from continuity equation. Am I right? It's only my guess. Please correct me.

Thanks in advance.

Peng

drivas
Posts: 33
Joined: Tue Aug 28, 2007 8:31 pm
Location: CICESE

Re: Open boundary CPP option for river?

#2 Unread post by drivas »

Hi,
You should include the river in the U/V points (option UV_PSOURCE) as well as in the RHO points (option TS_PSOURCE). I don't know how useful my comment can be (given your application), but I'm using radiation plus nudging in my open boundaries, except for 2D momentum (in such a case I use the Flather condition). I had a particular problem with the river I include in my domain, this didn't leave the domain completely, but a part of it followed the boundary as a current. I solved the problem applying some nudging to climatology to the tracers (temperature and salinity), but just within a narrow stripe along the boundary, in which the nudging decreased linearly from its maximum at the boundary to its minimum some points to the interior.
I hope this helps.
drivas

pengjia
Posts: 10
Joined: Thu Aug 21, 2008 4:24 pm
Location: UMCP

Re: Open boundary CPP option for river?

#3 Unread post by pengjia »

Hi drivas.

Thank you for your helpful comments. How did you apply radiation & nudging conditions to rivers? Did you modify the ROMS code or just put the river source points on your open boundaries?

I recall someone in this forum modified the ROMS code and created a new CPP called PSOURCE_FSCHAPMAN or something like that. Can anybody else share your experience dealing with river boundaries?

Thank you.

Peng

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