This Service will allow authorised users to retrieve and list MARS data from outside the ECMWF facilities. Users within ECMWF Member and Co-operating States may contact their Computing Representative to obtain access to MARS. All other users may request a username and password, following these instructions. In this page you will find the step-by-step guide to install the ECMWF Web API client and create your own MARS Requests. We strongly recommend you that you get familiar with MARS. |
For those used to the MARS system, it is worth noting that the client that you will install in your system is a Web API service interface that forwards the request to our systems and expects a single output file. It has no knowledge of internal ECMWF libraries such as libemos or grib_api, these operations are performed in our internal servers. Therefore, not all the functionality of the full MARS client is available, like multi-target, compute, etc... This method is only supported on UNIX systems. It requires Python. |
Steps: |
(Optional) To follow this guide, we recommend you to have a directory in your $HOME space called "mars".
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Download the mars python script: mars. You have to give execution permission to the file and put it in a location in your PATH. If the file has been downloaded to ~/mars/bin, you have to execute:
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There are two ways of doing this:
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Example script Retrieval of sea surface temperature for the first 10 days of May 2002, all synoptic times. It retrieves 40 fields.
Save this script as mars.req and execute:
The command should generate a sst.grib file containing the retrieved 40 fields in GRIB format.
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To check the Data availability you should have Access to the MARS Catalogue. Please note that the MARS catalogue is a super-set of the Archive catalogue.
you will view all the experiments that are available from our archive. We strongly recommend you to to navigate through MARS Catalogue to become familiar with the availability of our archive. You may select a class and start navigate trough the contents. Please take into account some considerations about the content:
The web-application above will help you to check and understand the availability. For any kind of selections the system will update the attributes in a dynamic way to reflect the current availability. (i.e. if you change the steps some parameters will be added or removed).
You can also use list action with output=cost keyword to see the available data and its cost without need to retrieve it. This is useful to check the amount of data and number of tapes that your request will need to access. If your request takes longer than expected, it is a good practice to check its cost.
Spend some time to understand how it works, make some selections try to execute the MARS scripts. |
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See Brief MARS request syntax page. |
Training material (slides, pdf): MARS introduction and basic concepts |
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