GeoZarr SWG Monthly Meeting, 4 March 2026

Meeting Purpose

Review GeoZarr progress, governance, and the V1 roadmap.

Key Takeaways

• CF alignment is active. CF discussions are exploring two paths: a backwards-compatible NetCDF-to-Zarr mapping and a native Zarr-first convention. The CF Governance Panel meets March 19 to discuss next steps.
• V1 release candidate at risk. The May 2026 target is threatened by a lack of independent implementations. The group will define stricter criteria for "implementation" to ensure robustness.
• OGC governance requires clarification. The standard OGC IP clause (contributions become OGC property) is a major concern. Max J. will meet with OGC staff to understand its practical implications for GeoZarr.
• New resources launched. A public website, an online validator, and a Python toolkit (geozarr-toolkit) are now available to improve accessibility and aid development.

Topics

V1 roadmap and new resources

• V1 roadmap tracking.
  • Progress is tracked via GitHub issues and a project board in the geozarr-spec repo.
  • Milestones include document tool compatibility and create conformance data set suite.
  • "To-do" issues are available for new contributors.
• New resources.
  • Website: a central landing page for new users, linking to conventions, the spec repo, and the OGC page. It also syncs progress from the GitHub project board.
  • Online validator: a web app for validating public Zarr stores against GeoZarr conventions.
    • Feedback: the validator should be updated to check all conventions and report on each, not just pass/fail.
  • geozarr-toolkit: a Python library that powers the validator, used for creating and validating conformant metadata.

CF alignment

• CF GitHub discussion. A lively discussion is underway, exploring two main approaches:
  1. Backwards-compatible: mapping existing NetCDF / CF datasets to Zarr (e.g., via the NCZarr library).
  2. Native Zarr-first: developing a new CF convention designed specifically for Zarr, not tied to NetCDF.
• CF governance action.
  • The CF Governance Panel will meet March 19 to discuss how to manage these different paths.
  • Dave Blodgett is preparing a Zarr-focused proposal for the CF discussions.
• GeoZarr strategy. The SWG will wait for Dave Blodgett's proposal before engaging further, as the CF community needs to resolve its internal strategy first.

Implementations and V1 readiness

• V1 release candidate (RC) target: May 2026.
• Blocker. The current definition of "implementation" is insufficient for moving conventions to "Candidate" maturity.
  • Rationale: the requirement for three implementations is met, but they are all driven by one project (EOPF), which lacks independent verification.
• Proposed solution. Define stricter criteria for what constitutes a valid implementation. Ideas include:
  • Require implementations from different organizations.
  • Require support for different data sets (e.g., climate, radar).
  • Specify read-only vs. read/write capabilities.
• Implementation matrix.
  • GDAL: done (pending release).
  • OpenLayers: in progress, with known issues (e.g., fixed-scale offset).
  • rioxarray: merged (pending release).
  • EOPF: needs documentation updated from GeoZarr 0.4 to the current Zarr convention.
• Gaps identified.
  • R: Patrick will investigate adding his CF-on-NetCDF library.
  • Julia: Patrick will contact Zarr / NetCDF users in the Julia community.

OGC governance and hosting

• SWG voting membership.
  • Process: OGC members must agree to the contribution statement in Agora. Voting rights are granted after a 30-day waiting period.
  • Action: all OGC members who wish to vote should complete this step.
• OGC IP clause.
  • Issue: the required OGC contribution statement specifies that "any contributions... shall be owned by OGC."
  • Concern: this clause is problematic for an open-source project like GeoZarr.
  • Context: GeoZarr is a "regular standard" (not a "community standard") to leverage OGC's governance structure, which may trigger this clause.
  • Action: Max J. will meet with OGC staff (Scott Simmons, Greg) to clarify the practical implications.
• HackMD hosting.
  • Problem: the previous HackMD was on a personal account and hitting free-tier limits.
  • Solution: a new GeoZarr team account was created.
  • Action: Tyler will join Max J. as an admin to reduce the "bus factor."
• GitHub organization.
  • Decision pending: an issue asks whether GeoZarr should remain under zarr-conventions or get its own GitHub org for stronger branding.

Next Steps / Action Items

• Max J.
  • Meet with OGC staff (Scott Simmons, Greg) to clarify the IP clause and governance rules; report back.
  • Draft a PR defining stricter criteria for "implementation" to qualify conventions for "Candidate" maturity; request feedback.
  • Open an issue on implementation-matrix notes and disclaimers; assign Emmanuel.
  • Post Dave Blodgett's CF / Zarr link in the GeoZarr spec CF-alignment issue; tag Ethan.
  • Schedule an offline chat with Ethan on the OGC SWG chair approach.
  • Update the online validator to check all conventions and report per-convention results.
• Patrick
  • Email Max J. details about his R CF-on-NetCDF library for potential inclusion in the implementation matrix.
  • Contact the Julia community to identify Zarr / NetCDF / CF users; share contacts.
• Tyler
  • Join Max J. as an admin on the new GeoZarr HackMD team.
• All
  • Review the GitHub issue on creating a dedicated GeoZarr GitHub organization and provide feedback.