CF Convention Alignment

[maxrjones]

Summary

Align GeoZarr conventions with the Climate and Forecast (CF) conventions by developing a proposal for registering CF metadata via GeoZarr's convention mechanism. This enables interoperability between the GeoZarr and CF communities.

Background

The GeoZarr charter identifies alignment with CF conventions as a potential area of contribution. At the February 2026 SWG meeting, Patrick Van Laake and Guilherme Castelao volunteered to lead this effort, unblocking a key dependency. Chris Little has also been coordinating with CF leadership (David Hassel, Jonathan Gregory, UK Met Office) for formal CF convention involvement.

A straw-man proposal for registering CF conventions via GeoZarr's zarr_conventions mechanism has been drafted and needs review - https://github.com/zarr-conventions/CF

Acceptance Criteria

• Straw-man proposal reviewed by CF alignment leads (Patrick Van Laake, Guilherme Castelao, any CF leadership)
• Meeting held with Patrick Van Laake, Guilherme Castelao, Chris Little, and CF leadership to discuss approach
• Proposal for how CF metadata maps to the zarr_conventions registration mechanism
• Identified areas of overlap and potential conflict between CF and GeoZarr conventions
• Recommendation on whether CF attributes should be a GeoZarr convention or a separate registration
• Feedback gathered from CF community contacts
• Documentation of alignment approach for SWG review

Key Questions

1. Should CF-on-Zarr be registered as a GeoZarr convention with its own UUID, or remain independent?
2. How do CF coordinate variables relate to the spatial: convention?
3. How do CF grid_mapping attributes relate to the proj: convention?
4. What is the minimal CF subset that GeoZarr should acknowledge or require?
5. How do we handle cases where CF and GeoZarr encode the same information differently?

Leads

• Patrick Van Laake — CF alignment lead
• Guilherme Castelao — CF alignment lead
• Max Jones — Scheduling and coordination

Next Steps

1. Max to schedule initial meeting with Patrick, Guilherme, and Chris Little
2. Review straw-man proposal at that meeting
3. Identify concrete alignment actions
4. Report back to SWG at next monthly meeting

Dependencies

• Straw-man proposal (drafted, needs review) - https://github.com/zarr-conventions/CF

References

• CF Conventions
• Zarr Conventions Framework
• GeoZarr Charter, Section 4 (potential contributions to CF)