Dear ROMS users,
I was wondering why we set minimum depth in ROMS ?
About minimum depth
About minimum depth
Joonho Lee
- arango
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Re: About minimum depth
![Idea :idea:](./images/smilies/icon_idea.gif)
I gave you a good clue... As a homework, you can figure out the rest...
Re: About minimum depth
Thnank you for your reply, Dr. Arango. Good clue.
So, we have to set non-zero value as a minimum depth in order not to make the vertical level thickness zero.
-JH
So, we have to set non-zero value as a minimum depth in order not to make the vertical level thickness zero.
-JH
Joonho Lee
- arango
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Re: About minimum depth
Yes, that's part of the answer. But you still have to check the
governing equations. If the vertical thickness (Hz) is zero, what would happen to the vertical viscosity and diffusion terms? Then if you search for oHz in the code, you will notice that the internal array oHz is in several routines of the numerical kernel. Notice that oHz=1/Hz.
This is the kind of analysis that users with curiosity need to carry out to discover what are the assumptions that we need to make when coding the continuum governing equations in numerical models. This kind of analysis is needed to determine was is the appropriate minimum depth (hmin) for a particular application, for instance. This is going to control the vertical time step limitation (CFL) as a function of your specified number of vertical levels. In terrain-following coordinates, we need to have all the vertical levels to exist at the minimum depth.
So now you know why we cannot have a water column with a total thickness of zero![Exclamation :!:](./images/smilies/icon_exclaim.gif)
I added an entry to the FAQ web page of
WikiROMS and hope that this issue is very clear and never discussed again in the forum.
![Arrow :arrow:](./images/smilies/icon_arrow.gif)
This is the kind of analysis that users with curiosity need to carry out to discover what are the assumptions that we need to make when coding the continuum governing equations in numerical models. This kind of analysis is needed to determine was is the appropriate minimum depth (hmin) for a particular application, for instance. This is going to control the vertical time step limitation (CFL) as a function of your specified number of vertical levels. In terrain-following coordinates, we need to have all the vertical levels to exist at the minimum depth.
So now you know why we cannot have a water column with a total thickness of zero
![Exclamation :!:](./images/smilies/icon_exclaim.gif)
I added an entry to the FAQ web page of
![Arrow :arrow:](./images/smilies/icon_arrow.gif)
Re: About minimum depth
Thank you for your detailed comment and adding an entry of WikiROMS.
That is kind of you to do so.
And I'm sure that users can get this fundamental information via the WikiROMS.
Regards,
-JH
That is kind of you to do so.
And I'm sure that users can get this fundamental information via the WikiROMS.
Regards,
-JH
Joonho Lee
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- Location: School of Marine Science, University of Maine
Re: About minimum depth
Considering a wet-dry ROMS, We can have a grid covering a domain without worrying about minimum depth. Just let the water flow around following fluid mechanics. In that sense there is no minimum depth.
Of course, practically wet-dry scheme usually still has a minimum depth for a grid point to be considered a wet point.
Of course, practically wet-dry scheme usually still has a minimum depth for a grid point to be considered a wet point.
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Re: About minimum depth
if defind WER_DRY, the Hmin how to be set?