Beginning with netCDF version 4.8.0, the Unidata netCDF group has extended the netCDF-c library to provide access to cloud storage (e.g. Amazon S3) by providing a mapping from a subset of the full netCDF Enhanced (aka netCDF-4) data model to a variant of the Zarr data model that already has mappings to key-value pair cloud storage systems. The netCDF version of this storage format is called NCZarr.

This document defines the variant of the netcdf-c library API that can be used to read/write NCZarr dataset. Additionally, any special new flags or other parameter values are defined. It is expected that this document should be consistent with the NetCDF ZARR Data Model Specification [1].

This document defines the initial netcdf Zarr (NCZarr) data model to be implemented. As the Zarr version 3 specification progresses, this model will be extended to include new data types.

The Unidata NetCDF group is proposing to provide access to cloud storage (e.g. Amazon S3) by providing a mapping from a subset of the full netCDF Enhanced (aka netCDF-4) data model to one or more existing data models that already have mappings to key-value pair cloud storage systems.

The initial target is to map that subset of netCDF-4 to the Zarr data model [1]. As part of that effort, we intend to produce a set of related documents that provide a semi-formal definition of the following.