Icechunk ERA5

Description

An analysis-ready, cloud-optimized (ARCO) edition of ERA5, the fifth-generation global reanalysis from the Copernicus Climate Change Service (C3S) at ECMWF. Provided as a single Icechunk + Zarr v3 store on AWS S3, this version enables efficient, scalable access to global reanalysis data for weather, climate, and ML/AI applications. Managed by Earthmover.

ERA5 provides hourly estimates of atmospheric, land-surface, and ocean variables from 1940 to 2025 on a ~31 km (0.25°) global latitude-longitude grid. This Earthmover edition delivers 35 single-level (surface) variables, 8 pressure-level variables on 13 isobaric levels (50–1000 hPa), and a curated 500 hPa geopotential slice, all with CF-1.7 compliant metadata.

The store is organized into three top-level groups (single, pressure, and 500hPa). Each group is provided with two complementary chunking strategies that hold identical data: a "spatial" layout (one full global map per hour) optimized for map-style and regional queries, and a "temporal" layout (long time series in small spatial tiles) optimized for time-series extraction, location-based analysis, and ML training workflows. Arrays are stored as Float32 with PCodec compression for high compression ratios. Only lossless compression has been applied; data values are bit-for-bit identical to raw ECMWF NetCDFs.

The data is provided in the Icechunk format. Icechunk is an open source tensor storage engine that augments Zarr with transactional updates, version history, and an optimized, Rust-based I/O path for maximum performance in the cloud.

An interactive browser for the data is available via the Earthmover Data Marketplace: https://app.earthmover.io/marketplace/6a19bcfe9aa6e97720a2fad2?tab=dataset

Earthmover maintains two complementary ERA5 datasets:

• This one, updated at quarterly frequency, available free under an open license.
• A low-latency version with the same variables, but updated daily with the latest ERA5T near-real-time data. This is available at a competitive price and comes with a strong SLA. See ERA5 (Daily Updates) on the Earthmover Data Marketplace.

If your organization is using ERA5 in a serious operational context, please consider subscribing to the low-latency version of this dataset. Paid subscribers for the low-latency dataset are what make it sustainable for us to provide this high-quality free, open dataset. Contact sales@earthmover.io to learn more.

The ERA5 dataset is public and can be opened directly from S3 with the Icechunk and Xarray libraries:

import icechunk
import xarray as xr

storage = icechunk.s3_storage(
    bucket="earthmover-icechunk-era5",
    prefix="icechunkV2",
    region="us-east-1",
    anonymous=True,
)
repo = icechunk.Repository.open(storage)
session = repo.readonly_session("main")
ds = xr.open_zarr(session.store, group="single/spatial", consolidated=False, chunks=None)

Alternatively, you can use the Arraylake client for a more concise syntax.

from arraylake import Client
import xarray as xr

client = Client()
client.login()

repo = client.get_repo("earthmover-public/era5")
session = repo.readonly_session("main")
ds = xr.open_zarr(session.store, group="single/spatial", consolidated=False, chunks=None)

The dataset is assembled from the NSF NCAR Curated ERA5 archive and the Copernicus Climate Data Store. It is widely used for ML/AI training, climate and weather research, extreme-event analysis, and applications such as renewable energy siting.

Update Frequency

Quarterly (every three months); historical reanalysis covering 1940 to 2025

License

Creative Commons Attribution 4.0 International (CC-BY 4.0) - https://creativecommons.org/licenses/by/4.0/

Documentation

https://app.earthmover.io/marketplace/6a19bcfe9aa6e97720a2fad2

Managed By

Earthmover

See all datasets managed by Earthmover.

Contact

hello@earthmover.io

How to Cite

Icechunk ERA5 was accessed on DATE from https://registry.opendata.aws/earthmover-era5. This dataset was generated using Copernicus Climate Change Service information 2026. Copernicus Climate Change Service, Climate Data Store, (2023): ERA5 hourly data on single levels from 1940 to present. Copernicus Climate Change Service (C3S) Climate Data Store (CDS). DOI: https://doi.org/10.24381/cds.adbb2d47 (Accessed in 2026). Copernicus Climate Change Service, Climate Data Store, (2023): ERA5 hourly data on pressure levels from 1940 to present. Copernicus Climate Change Service (C3S) Climate Data Store (CDS). DOI: https://doi.org/10.24381/cds.bd0915c6 (Accessed in 2026). Historical backfill from the NSF NCAR Curated ERA5 archive: European Centre for Medium-Range Weather Forecasts. 2019, updated monthly. ERA5 Reanalysis (0.25 Degree Latitude-Longitude Grid). Research Data Archive at the National Center for Atmospheric Research, Computational and Information Systems Laboratory. https://doi.org/10.5065/BH6N-5N20.

Usage Examples

Tutorials

• ERA5 sample data - access examples and documentation by Earthmover
  

Tools & Applications

• era5-qc - verify ERA5 data against the original ECMWF CDS source by Earthmover
  

Publications

• Low Latency Icechunk ERA5 Now Available on the Earthmover Data Marketplace by Ryan Abernathey
  
• The ERA5 global reanalysis by Hersbach et al 2020