ENH: 2D chunks for all

[jklymak]

This allows 2D chunking for all mds files, not just the LLC cases.

This is a total hack at this point/proof of concept. However, it works for me, and allows me to get 2-D chunks and parallel work on a machine that doesn't have enough memory for my model run (for some reason I can't discern - each variable is only 5 Gb).

• needs docs
• needs tests
• probably needs to be properly interested with the other chunking options.

with xm.open_mdsdataset(data_dir, prefix=['means'], 
                                endian="<", geometry='cartesian',
                                chunks="2D") as ds:
   print(ds)

Here Nz=400:

...
Data variables:
    VVEL     (time, Z, YG, XC) float64 dask.array<chunksize=(1, 1, 1216, 1440), meta=np.ndarray>
    UVEL     (time, Z, YC, XG) float64 dask.array<chunksize=(1, 1, 1216, 1440), meta=np.ndarray>
    THETA    (time, Z, YC, XC) float64 dask.array<chunksize=(1, 1, 1216, 1440), meta=np.ndarray>
...

[mjlosch]

@jklymak I realise this is old, but would it be possible to contribute a short test for this new functionality?

[mjlosch]

@IvanaEscobar The tests all passed for python 3.11 to 3.13 on my local machine. Not sure what happened here, looks like it has to do with the CI itself.

[jklymak]

@mjlosch possibly this summer, but not very soon! I'll move to draft, or anyone is more than welcome to take this over.

[IvanaEscobar]

@mjlosch the error is addressed in PR #358 . The CI needed updated gfortran compilers in each environment tested.