From 18th October at 15:00UTC, our FTP server has changed from ftp://dissemination.ecmwf.int  to ftp://aux.ecmwf.int

From 18th October 15:00UTC, no new data will be published on dissemination.ecmwf.int

Scope

The ECMWF FTP service provides access to real-time data from the CAMS global atmospheric composition system. For product documentation please see here. For a description of the current global model please see here (including information on system upgrades) . For other data access options please see here.

Please see the list of available atmospheric composition variables below and make sure your variables of interest are available. Should you require any additional species, please raise a request through the ECMWF Support Portal (ECMWF login required).

User accounts

To get access to CAMS global data, you need user accounts on the ECMWF website, and on the ECMWF FTP service.

  1. Log on to www.ecmwf.int. (If you do not have an account create one)
  2. Read the Licence to Use Copernicus Products and accept the license at the bottom of the page.
  3. Contact us by creating a ticket through the ECMWF Support Portal, providing 
    1. the user name you used to log into www.ecmwf.int and accept the license
    2. for our service planning, a brief description of how you intend to use the data, and which chemical species are most relevant for you

Please note that the default limit per user is 10 active connections to the FTP server. There is also an overall limit across all users of 2,000 active connections.

Data location

FTP server

 ftp://aux.ecmwf.int

Data directories

/DATA/CAMS_GLOBAL/${YYYYMMDDhh}

/DATA/CAMS_GLOBAL_ADDITIONAL which contains individual files of surface level fields (model level 137).

/DATA/CAMS_GLOBAL_TEST/ which contains test data files

Retention policy

Forecast are kept for 3 days

File naming convention

The file naming convention is based on WMO guidelines as follows:

z_cams_c_ecmf_yyyymmddhhmmss_vvvv_tt_lt_sss_param.[grib|nc]

Where:

ecmf is the WMO location indicators. The list can be found here.
yyyymmddhhmmss is the base date and time of the forecast.
vvvv is a version or experiment identifier. prod will be used for operational products, test (or experiment ID) will be used for testing purposes, rean for reanalysis if needed.
tt type of data, fc - forecast, an - analysis
lt is the type of level. pl for pressure level products, sfc for surface fields, ml for model level fields
sss

 is the forecast hour time step. For accumulation and averages, it is the

end time. This number must be zero padded to 3 digits, e.g. step 24 is given as 024

param

 is the parameter short name as defined here

grib, nc

 is the format of a file, GRIB or NETCDF

Data organisation

The dataset is grouped by type of product (analysis or forecast), level type (surface parameter, pressure level or model level), by step or forecast range and by parameter. 

Examples:

z_cams_c_ecmf_20160704000000_prod_an_sfc_000_tchcho.grib  contains analysis field of total column formaldehyde computed on 7 July 2016 at 00:00 UTC.

z_cams_c_ ecmf_20160704000000_prod_fc_pl_012_co.grib contains all the pressure levels of +12 step CO fields from a forecast started on 7 July 2016 at 00:00 UTC.

z_cams_c_ ecmf_20160704120000_prod_fc_ml_012_go3.nc  contains all the model levels of step 12 O3 fields from a forecast which was started on 7 July 2016 at 12:00 UTC in NetCDF format.

Data format

Model level fields are in GRIB2 format. All other fields are in GRIB1, except for new parameters from cycle 48r1 (more details are available here). NetCDF format is also available.

From cycle 48R1, there are important changes to the GRIB encoding for model levels fields, relating to packing and GRIB tables. Please see this page for full details: Implementation of IFS cycle 48r1 for CAMS#ChangetoGRIBencoding

The 'packingType' can be changed using ECMWF's ecCodes:

# CCSDS -> simple

grib_set -r -s packingType=grid_simple in.grib2 out.grib

# Simple -> CCSDS

grib_set -r -s packingType=grid_ccsds in.grib out.grib2

Data availability

The latest model cycle based on the 00 UTC analysis is normally available by 10:00 UTC, the cycle based on 12 UTC analysis is available by 22:00 UTC.

After the data transfer to the ftp server is completed a manifest file is uploaded:

z_cams_c_ecmf_yyyymmddhhmmss_vvvv.manifest

The file is uploaded to the server only after all the data files have been successfully uploaded. The file contains a list of all the GRIB and NetCDF files in the cycle and their MD5 checksums in case you would like to verify data integrity.

List of available parameters

Data volumes per model cycle

The data volumes are based on the current CAMS experiment (link) and for guidance only.

Due to the new compression method used, the GRIB file sizes vary much more than before. In this table the numbers are averages.

* Please be aware that, the total volume will vary from one model run to the next one.



average file size (GRIB / NC)No. of fields per fileNo. of variablesNo. of files (GRIB or NC)Total size (GRIB)Total size (NC)
an_ml~ 82 MB/144 MB1373333~ 3 GB4.6 GB
an_pl~ 28 MB/28 MB253232~ 881 MB899 MB
an_sfc~ 1 MB/1.3 MB13030~ 33 MB38 MB
fc_ml~ 77 MB/44 MB137391599~ 120 GB68 GB
fc_pl~ 28 MB/8.3 MB25321312~ 35 GB10.7 GB
fc_sfc~ 1 MB/435 kB1333993~ 4 GB1.7 GB


Totals
6999

163 GB*

87 GB


This document has been produced in the context of the Copernicus Atmosphere Monitoring Service (CAMS).

The activities leading to these results have been contracted by the European Centre for Medium-Range Weather Forecasts, operator of CAMS on behalf of the European Union (Delegation Agreement signed on 11/11/2014 and Contribution Agreement signed on 22/07/2021). All information in this document is provided "as is" and no guarantee or warranty is given that the information is fit for any particular purpose.

The users thereof use the information at their sole risk and liability. For the avoidance of all doubt , the European Commission and the European Centre for Medium - Range Weather Forecasts have no liability in respect of this document, which is merely representing the author's view.

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