Can't open file when downloading too many variables

Software and Tools API
1

I seem to be facing an issue where if I download too many variables at once, the downloaded file seem to be corrupted.

Here is the code I use:

year = 2019
month = 1
targetFilePath = targetFolder / f'surface_{year}_{month}.nc'
request = {
        'product_type': ["reanalysis"],
        'data_format': 'netcdf',
        'download_format': 'unarchived',
        'variable': [
            '10m_u_component_of_wind',
            '10m_v_component_of_wind',
            '2m_dewpoint_temperature',
            '2m_temperature',
            'surface_net_solar_radiation',
            'surface_pressure',
            "total_precipitation",
            "instantaneous_10m_wind_gust",
        ],
        'year': [str(year)],
        'month': [
            str(month),
        ],
        'day': [
            '01', '02', '03',
            '04', '05', '06',
            '07', '08', '09',
            '10', '11', '12',
            '13', '14', '15',
            '16', '17', '18',
            '19', '20', '21',
            '22', '23', '24',
            '25', '26', '27',
            '28', '29', '30',
            '31',
        ],
        'time': [
            '00:00', '01:00', '02:00',
            '03:00', '04:00', '05:00',
            '06:00', '07:00', '08:00',
            '09:00', '10:00', '11:00',
            '12:00', '13:00', '14:00',
            '15:00', '16:00', '17:00',
            '18:00', '19:00', '20:00',
            '21:00', '22:00', '23:00',
        ],
        'area': [90, -180, -90, 180],
    }

client = cdsapi.Client()
client.retrieve('reanalysis-era5-single-levels', request).download(targetFilePath)

trying to open the resulting file with xarray will lead to:

NetCDF: Unknown file format

If I reduce the number of variables to, e.g., 5, it works without issue.

Any ideas?

Thanks!

2

Hi,
please have a look at the following link: Forthcoming update to the format of netCDF files produced by the conversion of GRIB data on the CDS

Thanks

3

Hi, I had the exact same issue and noticed two things after trying all possible combinations of settings:

  • download_format ‘zip’ does not work, only ‘unarchived’
  • I tried to download winds and waves, which both together did not work, only winds and only waves in separate files were producing nc files that could be opened

Its a bit strange as in the old version, there was no problem downloading different types of variables into one file.

4

Got it, thanks.

Downloading as zip worked for me and produces multiple files as you described on that other page.

Maybe a warning could be issued if someone tries to download it as one netcdf file?

Thanks for your help!