GeoZarr
Open conventions for geospatial Zarr. CRS, spatial transforms, multiscale pyramids, and climate metadata, composable into a single Earth-science profile.
What it does
GeoZarr is a set of composable Zarr conventions for storing multidimensional georeferenced grids. Each convention addresses a single concern and can be used on its own or combined: proj: records the CRS, spatial: records affine transforms between array indices and geographic coordinates, and multiscales records resolution pyramids. CF integration, reusing the existing NetCDF Climate & Forecast vocabulary, is under active discussion as an additional convention. A GeoZarr group is just a Zarr group, so any Zarr reader (zarr-python, xarray, zarrita.js) opens it without GeoZarr-specific code.
Why it matters
- One profile across stacks: xarray, GDAL, zarrita.js, deck.gl-zarr, OpenLayers, and others can all consume the same metadata
- Composable: use only what you need, layer in CRS without committing to a pyramid, or vice versa
- Inheritance: group-level
proj:andspatial:metadata cascade to child arrays, so a single CRS or transform covers a whole archive without per-array duplication - OGC standards track: developed by the OGC GeoZarr Standards Working Group, targeting Architecture Board review by summer 2026
Core conventions
| Convention | Namespace | Purpose |
|---|---|---|
| geo-proj | proj: | CRS via EPSG, WKT2, or PROJJSON |
| spatial | spatial: | Affine transforms from array indices to geographic coordinates |
| multiscales | multiscales | Resolution pyramids for tiling and overviews |
All three are at Proposal maturity in the Zarr Conventions Framework, targeting Candidate (three independent implementations) for V1. Conventions under consideration include CF in Zarr, DGGS in Zarr, and TileMatrixSet.
See it in action
Browse real GeoZarr datasets at inspect.geozarr.org. The in-browser rendering demos on this site, ECMWF and AlphaEarth Foundations, both load GeoZarr-conformant arrays directly into deck.gl-zarr, using proj: and spatial: for georeferencing and multiscales to pick the right pyramid level for the current zoom.