GeoZarr SWG Monthly Meeting, 4 February 2026

Meeting Purpose

To align on a roadmap for GeoZarr V1 and advance key convention work.

Key Takeaways

• V1 roadmap approved. A 3-milestone plan (RC, AB Review, SWG Vote) was approved to deliver GeoZarr V1 to the OGC Architecture Board this summer.
• CF alignment accelerated. Patrick Van Laake and Guilherme Castelao volunteered to lead CF convention alignment, unblocking a key dependency.
• EOPF Explorer V1 launched. The first production adoption of GeoZarr conventions (Spatial, Proj, Multiscales) for Sentinel data is now live, providing a critical real-world testbed.
• New requirements identified. The roadmap will incorporate new issues for richer observational metadata (Kathi Schleidt) and clearer CRS guidance (Patrick Van Laake).

Topics

Governance and roadmap

• New chair. Max Jones was formally elected chair. A co-chair is sought (OGC membership required).
• V1 roadmap. A 3-milestone plan was approved to guide work toward OGC standardization this summer:
  1. V1 Release Candidate (RC). Conventions reach "Candidate Stability" (mostly stable, breaking changes require new versions).
  2. V1 Architecture Board (AB) Review. Formal presentation to the OGC AB.
  3. V1 SWG Vote. Final vote by the SWG for official release.
• Issue tracking. All tasks will be tracked via GitHub Issues and a Project Board in the geozarr-spec repo.

Convention alignment and new requirements

• CF Conventions.
  • Problem. Previous outreach to CF leadership (David Hassell, Jonathan Gregory) yielded no response.
  • Solution. Patrick Van Laake and Guilherme Castelao volunteered to lead alignment.
  • Action. Max will schedule a meeting with the volunteers to review the straw-man proposal for registering CF via GeoZarr's convention mechanism.
• Coordinate Reference Systems (CRS).
  • Problem. The current CRS handling is implicit and needs clearer guidance.
  • Action. Patrick Van Laake will open an issue in the spatial convention repo with a concrete example of desired CRS metadata.
• Observational semantics.
  • Problem. GeoZarr lacks a mechanism for rich observational metadata (e.g., measurement methodology, property details).
  • Action. Kathi Schleidt will open an issue to propose a backwards-compatible extension, drawing on experience with CovJSON.
• Chunk manifest.
  • Proposal. Len Strnad presented a "chunk manifest" concept (a sidecar GeoParquet file) to index non-empty Zarr chunks, improving performance for sparse datasets.
  • Decision. This is an implementation optimization, not a spec-level concern. The discussion will continue in the chunk-manifest repo.

Adoption updates

• EOPF Explorer V1.
  • Status. Launched as the first production adoption of GeoZarr conventions (Spatial, Proj, Multiscales) for Sentinel data.
  • Tech stack. Uses OpenLayers and TiTiler.
  • Performance. Currently uses float32 due to a fixed-scale offset limitation in Zarr. Performance will improve significantly once this is resolved.
• rioxarray.
  • Status. The first PR creating a framework for GeoZarr conventions was accepted.
  • Next. Emmanuel Mathot will submit a PR to add Spatial and Proj convention support.
• Convention maturity.
  • Proposal. Elevate conventions to "Candidate" status after 3 implementations, then to "Stable" upon the final GeoZarr V1 vote.
  • Action. Emmanuel Mathot will track implementation status in a new issue.

Next Steps / Action Items

• Max Jones
  • Create GitHub issues and a V1 project board; convert the 15 issues and email an Agora recap.
  • Email Jonathan Gregory and David Hassell re: CF alignment.
  • Assess the CF-on-Zarr proposal and open issues in the CF repo.
  • Schedule a CF alignment call with Patrick Van Laake, Guilherme Castelao, and Chris Little; send a poll to find a time.
  • Create a GeoZarr FAQ in the spec repo and tag new members (including Kathi); email Kathi re: GitHub access and tagging.
  • Update the Agora landing page with links to all relevant Zarr convention repos.
• Patrick Van Laake
  • Open an issue in the spatial convention repo with a concrete example for CRS guidance.
  • Review Spatial / GeoProj CRS handling and open issues with examples.
• Kathi Schleidt
  • Open an issue to propose a backwards-compatible extension for rich observational metadata.
• Emmanuel Mathot
  • Track implementation status of the Spatial, Multiscales, and GeoProj conventions in a new issue; summarize at the next meeting.
• All
  • Review the V1 roadmap and provide feedback before the next meeting.