These pages describe the keywords which can be used to retrieve and manipulate MARS data or to request real-time data in dissemination.

Unless stated otherwise, MARS keywords have the same meaning when used with the MARS client (only available on ECMWF computers) or the Web API.

Please note the following limitations:

• not all possible combinations keyword = value will name a field in the archive. Therefore, some syntactically correct requests will not retrieve anything if the data they represent has not been produced/archived
• certain directives have only a meaning when requesting specific datasets and should be ignored or set to off for other datasets
• not all keywords can be used with all interfaces