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EUMETSAT Data Store — Data Tailor#

Data Tailor is EUMETSAT's server-side customisation service (api.eumetsat.int/epcs/) — the analog of NASA's Harmony. It subsets (ROI crop), reprojects, and reformats products on the server before delivery. earthlens reaches it through a dedicated tailor= knob on download().

tailor= vs aggregate= — spatial vs temporal#

These are two different operations and two different knobs:

Knob Operation Where it runs
tailor=TailorConfig(...) spatial — reproject + ROI crop + reformat server-side (Data Tailor)
aggregate=AggregationConfig(...) temporal — reduce a time axis (mean/sum/…) client-side (pyramids)

aggregate= is not implemented for EUMETSAT and raises NotImplementedError (it is the temporal reducer, unrelated to Data Tailor). Use tailor= for server-side spatial customisation. The two compose: tailor a product server-side, then reduce the result client-side.

Usage#

from earthlens.earthlens import EarthLens
from earthlens.eumetsat import TailorConfig

el = EarthLens(
    data_source="eumetsat",
    start="2024-06-01",
    end="2024-06-01",
    variables={"s3-olci-l1-efr": ["OLL1EFR"]},
    lat_lim=[50.0, 52.0],
    lon_lim=[-1.0, 1.0],
    path="examples/data/eumetsat",
)

paths = el.download(
    tailor=TailorConfig(
        format="geotiff",       # -> Chain.format ("geotiff", "netcdf4", …)
        crs="geographic",       # -> Chain.projection
        bbox=(-1.0, 50.0, 1.0, 52.0),  # (west, south, east, north); optional
    ),
)
# paths -> the customised GeoTIFF(s), read with pyramids like any raster

TailorConfig fields:

  • format — Data Tailor output format (default "geotiff").
  • crs — target projection (default "geographic").
  • bbox — optional (west, south, east, north) crop. When omitted, the request's own lat_lim / lon_lim become the ROI.
  • filter — optional list of band / layer names to keep.
  • quicklook — request a quicklook rendering (default False).

The Data Tailor product-type is not set by the user — it comes from the resolved catalog row's tailor_product_type.

Eligibility — not every collection is tailorable#

Data Tailor supports a fixed registry of product types. A catalog row is Data-Tailor-eligible only when it carries a tailor_product_type; the curated catalog marks 83 eligible collections (MSG SEVIRI, MTG FCI, Metop ASCAT / IASI / AVHRR / GOME-2, Sentinel-3 OLCI / SLSTR / SRAL, Sentinel-6, OSI SAF SST, …). Notably Sentinel-5P TROPOMI and OSI-SAF sea ice are not tailorable by this service.

Multi-channel / vector collections use a representative product type

A few eligible collections (e.g. mtg-amv, the ASCAT wind and Lightning Imager products) are output_kind: vector and/or span several Data Tailor per-channel products. Their tailor_product_type records one representative product from the registry — so eligibility is correct, but the default format="geotiff" may not be the meaningful output for a swath / vector collection (prefer format="netcdf4"), and a specific channel may need its own product type. Verify the mapping against your use case before relying on it.

A tailor= request against a non-eligible dataset raises a clear error:

el = EarthLens(data_source="eumetsat", variables={"s5p-l2-no2": ["NO2"]}, ...)
el.download(tailor=TailorConfig())
# ValueError: EO:EUM:DAT:0076 not Data-Tailor-eligible; download native
# (no tailor=) and reduce client-side with pyramids.

Lifecycle, quota, and reliability#

Each matching product is customised independently: submit → poll to a terminal state (DONE / FAILED / KILLED) with bounded backoff and a timeout → stream the output(s) to path → delete the customisation.

Data Tailor quota

Every customisation is delete()d after streaming — including on failure (in a finally). The Data Tailor account quota is limited, and orphaned customisations exhaust it. If you see a quota error, delete stale customisations (eumdac.DataTailor(token).customisations) or wait.

Reliability notes:

  • The EPCS endpoint intermittently returns 502 Bad Gateway; a transient submit failure is retried a few times with backoff.
  • A FAILED / KILLED customisation raises a RuntimeError carrying the tail of the server log; a job that never finishes raises TimeoutError.

Account must be download-authorised

Data Tailor pulls the input product from the Data Store server-side using your token. If your account has not accepted a collection's licence (or lacks Data Store download entitlement), the customisation fails with a 403 Forbidden at the download step — accept the licence in the EUMETSAT portal for that collection.

Reading native SEVIRI / FCI#

Tailoring to geotiff / netcdf4 yields a pyramids-readable raster. Native SEVIRI / FCI products (without tailor=) still need a satpy reader bridge in pyramids (a separate cross-repo follow-on) before they can be read client-side — tailoring to GeoTIFF sidesteps that.