Bathymetry for ocean model at any resolution

I know that bathymetry has been a pain in the neck and that people have evolved artistic talent in modifying bathymetry and opening/closing channels etc.

Can we collect here the accumulated knowledge so that, e.g., CliMA’s efforts (cc @glwagner) don’t need to reinvent the wheel? Is these papers documented anywhere?

What we would like to be able to do is to take the ETOPO super-high resolution bathymetry and be able to coarsen it to the resolution we want to run (e.g., 2, 1, 1/2, 1/4, 1/10, 1/12, 1/25, … whatever).

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@micael has been working on this here: GitHub - COSIMA/domain-tools.

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I have been using these tools successfully to create th 1/20th panan bathymetry and have a script that calls all functions in the correct order if that would be of any help?

Thanks both!

I am more interested on the procedure rather than scripts since I don’t know FORTRAN myself. @micael is there documentation that goes along with these code? E.g. not so much how to run them (as I see in the readme) but more on what the scripts do.

I’d like to demystify what the scripts are doing? What are the necessary and crucial steps in creating bathymetry file for a particular resolution? I know (from just overhearing lots of discussions) that just getting the ETOPO high-res bathymetry and coarsening it to the resolution we want simply won’t do the job. What else needs to be done?

Leaving us hanging @navidcy

I agree a more general overview about the process, and why each step is necessary, would be helpful.

Deleted it… it was a typo.

I guess I/we are aspiring for a documented reproducible process. Something that does not require bathymetry-magicians (which is how I currently view the process…)

@navidcy I’ve got on my TODO list to add some more detailed instructions and explanations about the part of the process I’m familiar with. Ideally other people in the community can cover the rest at some point.

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The ACCESS-OM2 1deg and 0.25deg topography were created with these scripts

but some of this processing is only needed for a B grid and unnecessary for a C grid- see 1/20° topography · Issue #12 · COSIMA/mom6-panan · GitHub

There is a lot of ACCESS-OM2 (B-grid) topography-related discussion here

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How come nobody has written a paper on this yet? Wouldn’t that be a great opportunity to gather the knowledge so that it can be reproduced in the future?

Thanks @aekiss!! I’ll look into those issues!

The processes we use are fully reproducible but not completely automated, because we still need hand-edits (especially at low resolution) for points where the mean of the underlying high-resolution dataset (eg. GEBCO) would misrepresent an important feature, e.g. the depths of sills and channels that control important water mass exchanges. This is basically a sub-gridscale parameterisation and can take multiple test runs to get right. On a B grid there are also non-advective points that can’t be fixed with our automatic tools and require somebody to eyeball it and make a judgement call.

When you get to very high resolution you start to be limited by the resolution of the underlying obs data, which is quite low-resolution away from multibeam tracks. There are methods around to fill in the fine details with something statistically reasonable, e.g.

Adding another relevant link: Topography generation · COSIMA/access-om3 Wiki · GitHub

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