Currently the interactive CDS forms don't allow users to perform a regional subselection or an interpolation of the selected data. However, both actions can be performed using the CDS API keywords area and grid with the same syntax used by ECMWF MARS and Web API.



import cdsapi

c = cdsapi.Client()

c.retrieve(
    'seasonal-monthly-single-levels',
    {
        'format':'grib',
        'originating_centre':'cmcc',
        'system':'3',
        'variable':'2m_temperature',
        'product_type':'monthly_mean',
        'year':'2007',
        'month':'11',
        'leadtime_month':['1','2','3','4','5','6'],
		'area' : '75/-25/10/60',
		'grid' : '2.5/2.5'
    },
    'download.grib')

More details about the syntax of area and grid in MARS/WebAPI can be found here.

Users must be aware of the following:


Currently the interactive CDS forms don't allow users to select NetCDF as data format for their retrievals. However, the value of the format keyword in CDS API scripts can be set to "netcdf" to obtain a netCDF version of the archived GRIB data.

Users must be aware that conversion to NetCDF is considered experimental and it is not guaranteed to work in all situations.

In this context,


The C3S seasonal forecast dataset is currently based on GRIB files archived at ECMWF's MARS archive. This implies, in some situations, accessing data not available online (on disk) but archived in the tape library.

The way the user selects the items to include in a single request can make a huge difference in the performance of the retrieval. To improve performance: