Quite the project! 🙂 I looked around much of the project, but am limiting my comments to what I see in the Items and Collections:

1. Is it worth adding something like source to the roles of the NetCDF assets that are on the collections?
2. Use of an average datetime (e.g., middle of a year) instead of setting it to null: is that the recommended practice? I've been avoiding setting datetime for long time period data since the data is not necessarily representative of state as of a single date.
3. Any opinions on use of singular rather than plural for units? For example, degree Celsius versus degrees Celsius.
4. spatial resolution in raster:bands?
5. sci:citation on the collections: fill in or delete: [indicate subset used] and Accessed [date]