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OceanDataStore - Discover

This is a User Guide for using the OceanDataCatalog to search, access and analyse our publicly available Analysis-Ready Cloud Optimsed (ARCO) ocean datasets.

What is the OceanDataCatalog?

OceanDataCatalog is a Python API which allows users to:

  • Explore the OceanDataCatalog Spatio-Temporal Access Catalog (STAC) containing collections of publicly available ocean model outputs stored in the JASMIN Object Store.
  • Search by collection of ocean data (e.g., EN4.2.2), standard variable names or data type (e.g., model / observation).
  • Access & subset Analysis-Ready Cloud-Optimised (ARCO) datasets as lazy xarray Datasets.

Background

What is STAC?

Spatio-Temporal Asset Catalogs (STAC) provides a standardized way to describe geospatial and temporal data so that it can be easily discovered & shared across many different platforms.

A STAC catalog organises datasets as a Collection of Items — each representing a geospatial asset (e.g., a model output file or satellite image) — and describes their spatial and temporal extent through structured metadata.

STAC is intentionally simple and extensible: it builds on widely used web standards (JSON and GeoJSON) and can describe geospatial assets stored in diverse formats, including large, cloud-optimized Zarr stores & Icechunk repositories.

Behind the OceanDataCatalog API, STAC catalogs are used to describe publicly available ocean model outputs produced by the National Oceanography Centre.

STAC Basics:

📁 Catalog — Container storing STAC Collections or other Catalogs - provides high-level metadata about its contents.

🗂️ Collection — Group of related Items that share common metadata, such as a modelling activity or model configuration.

📄 Item — Single spatio-temporal record within a Collection, typically representing one dataset instance (e.g., a model output file / dataset). Each Item includes geometry, timestamps, and links to a data Asset.

🧩 Asset — Actual data or file associated with an Item, such as a Zarr Store, NetCDF file, or Icechunk repository. Assets include URLs and media types which determines how data can be accessed.

NOC Ocean Modelling + STAC

National Oceanography Centre ocean model outputs are organised in the odc-stac Catalog, which serves as the highest-level STAC object in our hierarchy.

flowchart TD
    A["📁 Catalog\nnoc-stac"] --> B["🗂️ Collection\nnoc-npd-era5"]
    B --> C["📁 Catalog\nnpd-eorca1-era5v1"]
    B --> D["📁 Catalog\nnpd-eorca025-era5v1"]
    B --> E["📁 Catalog\nnpd-eorca12-era5v1"]
    C --> F["📁 Catalog\nr1i1c1f1"]
    D --> G["📁 Catalog\nr1i1c1f1"]
    E --> H["📁 Catalog\nr1i1c1f1"]
    F --> I["📄 Item  🧩 Asset\ne.g. eorca1-era5v1-1m…"]

The odc-stac Catalog is comprised of STAC Collections which group Items belonging to the same ocean modelling activity. In the example above, we have included the NOC Near-Present Day simulations produced using bias-corrected ERA-5 atmospheric forcing in the noc-npd-era5 Collection.

The noc-npd-era5 Collection contains three Catalogs corresponding to the three ocean sea-ice hindcast configurations (i.e., eORCA1, eORCA025, eORCA12) of the NOC Near-Present Day hierarchy.

Each npd-eorca{}-era5v1 Catalog in-turn contains one or more variant Catalogs containing the outputs associated with an individual ocean sea-ice hindcast simulation. Variant labels use a similar nomenclature to the Coupled Model Intercomparison Project (CMIP); r1i1c1f1 corresponds to Realisation = 1, Initialisation = 1, Configuration = 1, and Forcing = 1, where integers > 1 correspond to a variant of the original ocean sea-ice configuration.

Finally, each variant Catalog contains one or more Items associated with an Icechunk repository (Asset) containing time-mean NEMO ocean model outputs at a specified frequency. See the table below for annual, monthly and 5-daily mean examples:

Example Model Frequency
eorca1-era5v1-1y eORCA1 ERA5v1 Annual Means
eorca025-era5v1-1m eORCA025 Monthly Means
eorca12-era5v1-5d eORCA12 5-day Means

To improve the accesibility of our ocean model data, each Item is given a unique path-like identifier describing its relationship within the wider odc-stac Catalog.

For example, noc-npd-era5/npd-eorca1-era5v1/r1i1c1f1/eorca1-era5v1-1m identifies the Item containing monthly-mean variables for the eORCA1-ERA5v1 (1-degree) simulation contained in the NOC Near-Present Day ERA-5 Collection.