About topography

Discussion of how to use ROMS on different regional and basin scale applications.

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susonic
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About topography

#1 Post by susonic » Tue Oct 30, 2007 4:09 pm

Hi Everyone!
I'm a begginer with ROMS. And I wanna know about the topography which is used when we make grid.
My friend said to me that use etopo5. He just said "You have to use etopo5 becasuse etopo5 has better depth data than etopo2"
Are there any special difference between etopo2 and etopo5?
I can't figure out the difference. :cry:
Please answer the question.

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kate
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#2 Post by kate » Tue Oct 30, 2007 10:28 pm

ETOPO5 is on a 5 minute grid and is very smooth.

ETOPO2 is on a 2 minute grid and is a combination from several sources. It is from IBCAO in the Arctic and Smith and Sandwell for most of the rest of the world. The early Smith and Sandwell has some very funky values in shallow coastal waters.

GEBCO is on a 1 minute grid, costs a small fee, and is very smooth. It was made from digitized charts, digitizing the contours, so has a bias toward values of the contours from which it was made.

Smith and Sandwell have a new product on a 1 minute grid, much improved in the shallows from their previous versions.

Depending on your region of interest, there may be better products, especially coastal US for the contiguous states.

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susonic
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Thank you for your answer

#3 Post by susonic » Thu Nov 01, 2007 12:02 pm

ETOPO5 is 5minite grid... Then what does 5 minute grid mean?
(It might be a basic question but I don't know... :? )
And is ETOPO2 a confirmed data? Does it reliable?
And the last but most important question, I'm using ROMS2.1, so can you tell me where the menual is?

Many thanks... Kate! :P

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kate
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#4 Post by kate » Thu Nov 01, 2007 5:31 pm

A minute is 1/60 of a degree so 5 minutes is 1/12 degree resolution.

ETOPO2 is a combination of observations, each with their own errors. Some are ship soundings, some are gravitational from satellites. The gravitational ones are terrible close to land.

Manual? What manual? There is a SCRUM manual out there which is still useful but very dated. The numerics and many other details have changed, with the numerics being described in a new paper by Haidvogel et al. We have a contract with MMS to produce a draft updated manual by a year from now.

Also, there is an ongoing attempt to make a ROMS wiki. Contact Dave Robertson if you have things to contribute to it and would like the permission to do so.

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susonic
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#5 Post by susonic » Fri Nov 02, 2007 5:27 am

Thanks for your detailed reply. I really appreciate it ! :o

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