Dear Copernicus CDS Support Team,
I am using the reanalysis-cerra-pressure-levels dataset for tropospheric delay correction in InSAR processing (Sentinel-1, Etna, Italy). My study area is approximately 35°N–41°N, 12°E–17°E — a small corner of the CERRA domain.
The problem: Unlike ERA5, which supports the area parameter in CDS API requests to download a geographic subset, CERRA downloads the full European domain (1069×1069 Lambert conformal grid, ~190 MB per file) regardless of the area of interest. For a dataset with 475 acquisition dates × 3-hourly intervals, this results in ~90 GB of downloaded data, of which only ~0.7% covers my study area.
The request: Please add support for geographic bounding-box subsetting in CERRA CDS API requests, either:
A native area parameter (re-projecting the Lambert grid to a lat/lon subset on the server side), or
A spatial index/tile-based approach allowing download of only the relevant Lambert grid cells.
ERA5 precedent shows this is technically feasible. The bandwidth and storage savings for users working on small regional studies would be significant (~140× reduction in my case).
Workaround I am currently using: Download the full grid and subset in memory using cfgrib/xarray — functional but wasteful.
Thank you for considering this request. I am happy to provide further details.
Best regards,
Mohammad Mohseni Aref