River point source direction

General scientific issues regarding ROMS

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nganju
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Joined: Mon Aug 16, 2004 8:47 pm
Location: U.S. Geological Survey, Woods Hole
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River point source direction

#1 Unread post by nganju »

Hello everyone-
I have a river point source that runs into the domain in a diagonal fashion (does not run parallel to eta or xi directions). I am looking at effects close to this point source so I need the direction to be realistic near the source.

Do I need to split up the total discharge (Qbar in ANA_PSOURCE) into the two components and basically double the point sources (two for each boundary cell, one in the eta direction (Dsrc=0) and one in the xi direction(Dsrc>0))? Or is there a better way? thanks in advance....

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kate
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Joined: Wed Jul 02, 2003 5:29 pm
Location: CFOS/UAF, USA

#2 Unread post by kate »

I would look at what the direction of the coastline is in the area of interest. Does the land mask have a set of staircases there? Then you could divide the river input in each box into an east-west component and a north-south component. However, if the boundary runs strictly north-south (for instance) then I think it would be weird to put a north-south source as well as the east-west source.

We have a line source in the Gulf of Alaska, so we count up the number of boundary edges in the land mask, divide the entire flux into that many bits, and apply each bit to an edge. Any grid box with two walls of land mask will get two of the sources. Where there is a river, that gets added to the line source flux for those boxes.

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hetland
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Joined: Thu Jul 03, 2003 3:39 pm
Location: TAMU,USA

#3 Unread post by hetland »

I have also see people hack in an addition to the momentum equation one cell in from the source. That way, if you have a straight coastline, you can still have a river that comes in at an angle. However, I would not recommend this.

If you really want to resolve the details of the circulation field at this level, there is nothing else to do but resolve it with your grid. This will mean having *at least* three cells across the river mouth.

If you do this, you may need to create a grid that allows a river to come in at an angle. I would recommend Pavel Sakov's gridgen utility for this. Take a look at his website for examples:

http://www.marine.csiro.au/~sakov

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