Integration of Zarr with STAC Catalogs

[christophenoel]

As per very interesting discussion on Pangeo #3193, I believe that the unique nest-able hierarchy of Zarr provides an excellent opportunity to seamlessly fuse it with a STAC catalog.

This integration can be facilitated by including a .zstac object at each level of the Zarr hierarchy, alongside the existing .zgroup object. The .stac object would provide the corresponding STAC catalog information at that particular hierarchy level.

Furthermore, it's essential to distinguish between two types of metadata in this context:

• Discovery Metadata: These are properties that enable the search and discovery of a product. This metadata type is crucial for users to locate and identify datasets of interest within a large and complex catalog.
• Access Metadata: This refers to information necessary to understand and process the actual data contained in the datasets. It includes details about data format, structure, and other specifications crucial for data utilization. This type of metadata should be the focus of the GeoZarr specification.