GeoZarr SWG Monthly Meeting, 7 January 2026

Meeting Purpose

Sync on GeoZarr progress, address community concerns, and plan next steps.

Key Takeaways

• GeoZarr conventions are gaining traction. OpenLayers and TiTiler are implementing Multiscales, and the EOPF Explorer V1 (due end-of-month) uses the conventions as a foundational component.
• A key risk was identified. The CF convention community may be disengaged, leading to a potential split where GeoZarr serves only the GIS world and neglects critical climate data use cases.
• A path forward was defined. Max will draft a "strawman" proposal to formalize existing CF-on-Zarr patterns, ensuring the community's needs are met without waiting for formal CF committee action.
• A major usability gap is being closed. Wietze is developing a QGIS plugin to enable direct data analysis of GeoZarr files, moving beyond simple previews and making the format more accessible.

Topics

Community and governance

• Zarr governance update. Ryan announced the Zarr Steering Council is updating governance to clarify project boundaries and enable greater autonomy for sub-projects like GeoZarr. An update is expected this month.
• SWG co-chair needed. Christophe is seeking a co-chair for the SWG, as the current term ends in February. Max is the interim co-chair.
• Communication channel change. OGC is dissolving its Google Groups. The Agora platform and the CNG Slack channel (#geozarr) are the new primary communication channels.

GeoZarr convention adoption

• OpenLayers. Initial PR submitted for Multiscales support.
• EOPF Explorer V1 (ESA). Launching end-of-month, using Zarr conventions as a foundational component.
• ZarrLayer (CarbonPlan). Experimenting with Multiscales and GeoProj.
• TiTiler. Already compliant with Multiscales.
• GDAL. Evan is funded to add read-only support for Multiscales and GeoProj conventions.

Addressing the CF convention risk

• Concern. Chris raised a risk of the CF community being disengaged, potentially leading to a split where GeoZarr serves only the GIS world and neglects critical climate data use cases.
• Context. Ryan noted that Zarr has a 10-year history of successful, informal use with CF data, suggesting the primary challenge is formalizing existing patterns, not creating new ones.
• Proposed solution. Max will draft a "strawman" proposal to formalize these existing CF-on-Zarr patterns. This approach aims to provide a concrete document for feedback, addressing the community's needs without waiting for slow formal committee action.

Improving GeoZarr usability

• QGIS plugin for STAC. Wietze is developing a plugin to enable direct analysis of GeoZarr data within QGIS, moving beyond simple previews.
• GDAL implementation. Evan is funded to add read-only support for Multiscales and GeoProj conventions.
• GeoZarr examples repository. Max will update the repo with real-world examples from projects like EOPF Explorer to replace contrived ones.

Next Steps / Action Items

• Max
  • Draft a "strawman" proposal for formalizing CF-on-Zarr conventions, covering pillars plus the CF component, for the next meeting.
  • Update the GeoZarr examples repo with real-world use cases.
  • Post the GeoZarr examples repo / site update plan in the CNG Slack.
  • Create a GeoZarr issue to discuss consistent versioning.
  • Open a GeoZarr issue on CF-GeoZarr alignment and share it with Chris.
  • Email David Hassell and Jonathan Gregory regarding CF-GeoZarr alignment.
  • Email the UK Met Office regarding CF-GeoZarr support.
  • Merge outstanding GeoZarr PRs.
  • Compile and upload old Fathom notes to Agora.
• Wietze
  • Share the QGIS plugin for feedback in the CNG Slack #geozarr channel.
  • Post the STAC QGIS plugin PR in CNG Slack (GeoZarr and other channels).
• All
  • Consider nominating a SWG co-chair via Agora or email.
  • Review the versioning issue in the GeoZarr repo.