CAMS global forecast test data is available from 1 September 2022 onwards from the MARS archive. A daily updated test dataset is also available for the most recent 3 days on the FTP server.

MARS

If you have access to ECMWF systems you can retrieve CAMS global forecast test data from MARS archive using keywords:

class=mc
expver=0078

You can use this link to directly access the data in the MARS catalogue (please remember that ecCodes version 2.28.0 or later is required to handle the full range of parameters of current CAMS data).

Atmosphere Data Store (ADS)

If you don't have access to ECMWF computers but would still like to access a large subset of test data, you can retrieve fields from the cams-global-atmospheric-composition-forecasts-test dataset using the Copernicus Atmosphere Data Store API.

If you haven't done it yet, you will need to create an account and accept the terms of use of Copernicus Atmosphere Data Store.

The test data is only accessible through the ADS API service, and it is not possible to use the interactive web interface to download it.

You can use existing requests for the CAMS global atmospheric composition dataset by replacing the dataset name with "cams-global-atmospheric-composition-forecasts-test".

Example

Get (new) variables (available only from IFS Cycle 48r1):

• Anthropogenic secondary organic aerosol mass mixing ratio

• Biogenic secondary organic aerosol mass mixing ratio

• Secondary organic aerosol optical depth 550nm

• Glyoxal

• Total column glyoxal

Select only European domain, 10 dates and day 1 forecast:

import cdsapi

c = cdsapi.Client()

c.retrieve(
    'cams-global-atmospheric-composition-forecasts-test',
    {
        'date':          '2023-03-01/2023-03-10',
        'type':          'forecast',
        'format':        'netcdf_zip',
        'variable':    [ 'biogenic_secondary_organic_aerosol_mass_mixing_ratio',
                         'anthropogenic_secondary_organic_aerosol_mass_mixing_ratio',
                         'secondary_organic_aerosol_optical_depth_550nm',
                         'glyoxal',
                         'total_column_glyoxal' ], # See other variables at:
        'time':          '00:00',                  # https://ads.atmosphere.copernicus.eu/cdsapp#!/dataset/cams-global-atmospheric-composition-forecasts?tab=form 
        'leadtime_hour': [h for h in range(0,24)],
        'area':          [70, -35, 35, 60]         # [N,E,S,W] area boundaries
    },
    '/tmp/cams_test_20230301_10.nc.zip')

FTP dissemination

The test dataset is available through ECPDS FTP dissemination systems in these directories:

/DATA/CAMS_GLOBAL_TEST
/DATA/CAMS_GLOBAL_ADDITIONAL_TEST
/DATA/CAMS_EUROPE_BC_TEST

You can use your normal FTP account to access the data. Details about filenames convention or list of available parameters can be found at Copernicus Knowledge Base.

If everything else fails ...

... you can always contact us on ECMWF Support Portal creating a ticket "Request for CAMS global test dataset" as a subject and specify:

• which parameters and levels
• which time period
• forecast step / time frequency
• which geographical area
• which data format you require