Documentation for quad_utils is missing

[mgharamti]

What's the issue?

📚 Couldn't find any documentation for the quad utilities

Where did you find the issue?

Provide the location(s) of the issue: models/utilities/quad_utils_mod.f90

What needs to be fixed?

The quad utils are very important and extremely useful for doing interpolation in large models. The documentation of these utilities is missing. It should clearly distinguish between the different types of supported interpolation (e.g., regular, regular but nonuniform, irregular, dipole vs tripole, ...) and provide instructions on how to use them. Perhaps some example cases and developer tests would be nice.

[mgharamti]

@hkershaw-brown:

I showed this yesterday at stand-up. It turns out the ROMS grid is regular but with non-uniform spacing. So, instead of having to carry 2D arrays I just need a pair of 1D arrays (1 lon vector and 1 lat vector). As you can see, there is a huge memory saving especially for high number of nodes (e.g., 50% less memory in the case of 80 nodes). I was also able to run filter with 5 nodes which wasn't possible previously.

Right now, I'm doing other tests with filter. Once done, I'm thinking to add documentation for quad_utils and package them with the changes in the ROMS_rutgers model_mod in a single PR. How does that sound to you?

[hkershaw-brown]

@mgharamti cool, I'd put the quad_utils docs in a separate pull request that way one doesn't hold up the other.
Cheers,
Helen