We advise users to request ERA5 ocean and atmospheric variables separately if asking for the data in netCDF format.

Atmosphere parameters are stored on a 0.25° grid, while wave parameters are on a 0.5° grid. Unfortunately, the grib to netcdf conversion does not handle this situation well and gives the wrong coordinates for some of the wave parameters in the resulting netCDF file. The way to avoid this is to request atmospheric and wave variables in separate CDS requests.

Note that ERA5 ocean and atmospheric variables can be requested together if asking for the data in GRIB format.

1 Comment

  1. If the 'grid' keyword is specified explicitly in the API request, all datasets seem to be regridded to a common resolution and this problem is solved.

    So just specify:
    'grid': [0.5,0.5]       ... for downsampling of the atmospheric data or
    'grid': [0.25,0.25]  ... for upsampling of the wave data

    Climate Data Store (CDS) API Keywords