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What is Zarr Overview:

Zarr is one of these relatively newly adopted data formats specifically for a relatively new cloud-based data format specifically for improving access to N-Dimensional arrays. It is an effective way to store large N-dimensional data in the cloud and access the data in predefined chunks.  Zarr can be viewed as the cloud based version of HDF5/NetCDF files as it follows a similar data model.  Zarr does not come in a single file as NetCDF or HDF5 does but as a directory with chunks of data in compressed binary files and metadata describing the binary content in external JSON files.

The semantic mapping from the NetCDF Data Model to Zarr Data Model is as follows:

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Zarr V2 is the current stable version, Zarr V3 is considered experimental. 

How does GeoZarr differextension:

Zarr is a generic data format for Scientific Array Data.  Groups have found ways to store spatial metadata within the existing structure, however since this is not a single standardized method, users would have to create custom tools to retrieve those fields.  There is a GeoZarr Specification to provide a geospatial extension to the Zarr data format. GeoZarr can store multidimensional georeferenced earth observation data.

What is a Zarr (or GeoZarr) file organizedorganization:

With Zarr, Multiple arrays can be organized in hierarchies of groups. These arrays have the metadata as well as the actual chunked data. The .zarray describes how these binaries are encoded by giving unique key representations.

What support of the Zarr data format existsupport:

Creating and using Zarr data files at this time appears to be most well supported using one of these methods:

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4.). The R statistics package can also read Zarr files:  https://r-spatial.org/r/2022/09/13/zarr.html

5.). OpenLayers is working on a prototype for adding support: https://github.com/spacebel/geozarr-openlayers

Community StandardsAre other standards groups looking at Zarr:

The Open Geospatial Consortium approved Zarr V2 as a community standard (https://www.ogc.org/standards/community) in June 2022.   The documentation can be view at:  https://portal.ogc.org/files/100727

Are data providers using ZarrAvailable Zarr data sets: