Binning / interpolation to other grids

[briochemc]

It's unclear to me what is the best approach to use WOA data in different grids.

Bring the discussion from fprimeau/EARTHSS220#4 to here, because this is about WorldOceanAtlasTools.jl.

@fprimeau, this is where we should discuss how to do this interpolation / binning of the WOA data to grids such as that of OCIM.

[briochemc]

Will be using OceanGrids.jl for the ocean grids in AIBECS in the near future, so should test whatever interpolation with those grids.

[briochemc]

Discussion with @borisberanger:

1. If raw observations y_ij are available, use reported digits as measurement accuracy and build variance from it

2. If not, use "real variance" by computing sum of y_i^2

[briochemc]

Actually maybe I need to split this package up into one for just downloading WOA data to minimize dependencies (DataDeps + DataFrames mostly) and factor out the OCIM grid interpolations (and the OceanGrids dependency) to another package.

@simone-silvestri would that help your workflow? (Don't think you need my OceanGrids.jl dependency, which is a package I built a few years ago to store grid coordinates and metrics for my own usage in AIBECS.jl) This way we could turn this package here into a minimal dependency that really just deals with the names of URLs, files, and variables, and the interface limits itself to just the downloads.

[simone-silvestri]

In NumericalEarth we just need a way to download the data with the information about the grid. The regridding is handled directly by NumericalEarth, so in practice we do not need the interpolation infrastructure here. It is up to you if you want to split the repo, indeed it might make it more lightweight.