This page will give you a short overview on the recommended steps to retrieve data from MARS.
Explore the archive
The first step is to find out if the data you are looking for is actually archived in MARS. To do that, explore the MARS content by directly browsing the MARS archive catalogue. Alternatively, browse the dataset descriptions on the main ECMWF website which in turn contains links to the archive catalogue. Once the right data is found, you can use Web-MARS to "Check for availability", "Estimate download size" or to retrieve some sample data, just a few fields, to verify that this is the data you expect to get. In the MARS catalogue use Ctrl+ Left-Mouse-Button to select/unselect multiple parameters. If now you like to retrieve larger data volumes, make the data retrieve part of a script etc. you need to create a MARS request and pass is to the MARS client.Create a MARS request
Once you found the right fields, let Web-MARS create a MARS request as a starting point. This can be done by clicking on "View the MARS request" on the last page of the archive tree.To turn this initial request from Web-MARS into a complete request you just need to add a line to specify your target file, e.g.target="myfile". Now this request should be used to retrieve the data in a batch job.Retrieve the data in a batch job
As MARS requests can use considerable resources, the general recommendation is to retrieve data via serial batch jobs on the ecgate server. A full ecgate batch job which retrieves fields from MARS, applies some computation and transfers the resulting data to a remote site is provided with mars_ectrans.ksh. Once all this works fine, you might want to expand your script, e.g. to loop over several requests, write to multiple target files etc. For all modifications please consider the implications these might have reg. the resources like disk space and CPU time.
For further guidance please refer to other pages in this user guide.