Document surface obs xarray/nc format

[zmoon]

No description provided.

[zmoon]

Question: should we also add something here about getting new obs data sources into the tool "officially"? (e.g. start by opening Issue or Discussion in MM repo)

[blychs]

This looks great. I would reserve the "officially" for the developer's guide, but if you prefer to add them here, I don't see a problem with that either.
Just suggested a small change (time_local is only really required for regulatory metrics, for anything else the time variable to be used can already be set in the YAML file as ts_select_time)

[zmoon]

@blychs using time_local is also an option for the time series plot, used in many of the examples (plots.<group>.data_proc.ts_select_time: 'time_local'), so we may want to mention that as well.

[blychs]

adding mentions of timeseries

[blychs]

I'm ready to approve this PR once the one open conversation is closed.

[blychs]

Looks good to me.

[blychs]

I'm happy for this to get merged @rschwant

[rschwant]

I agree, looks good! @zmoon you can merge it when ready.

[zmoon]

Thanks @blychs for the help