Introduction

This is a brief introduction of the main request parameter syntax.

We recommend that you get familiar with the data and its availability using MARS Catalogue

You can also get the request syntax using " View MARS request " feature.

Syntax

verb,
 keyword1 = value1,
      ... = value2,
 keywordN = valueN
  • verb: action to be taken (e.g. retrieve, list, read)
  • keyword: a known MARS variable, e.g. type or date
  • value: value assigned to the keyword, e.g. Analysis or temperature

Retrieve example from "View MARS request":

MARS request
retrieve,
 class=ei,
 stream=oper,
 expver=1,
 levtype=sfc,
 param=165.128/41.128,
 step=0,
 grid=0.75/0.75,
 time=00,
 date=2013-09-01/to/2013-09-30,
 area=75/-15/30/42.5, 
 type=an,
 target="ei_sfc_165_41.grib"

MARS Request explanation

Identification Keywords

https://software.ecmwf.int/wiki/display/UDOC/Identification+keywords

#Specifies the ECMWF classification given to the data
  class=ei,

#Identifies the forecasting system used to generated the data when the same meteorological types are archived
  stream=oper,

#Is the version of the data, 1 is OPERATIONAL
  expver=1,

#Denotes type of level
  levtype=sfc,

#Meteorological parameter
  param=165.128/41.128,

#Determines the type of field to be retrieved:
  type=an,

Date and Time Keywords

https://software.ecmwf.int/wiki/display/UDOC/Date+and+time+keywords

#Specifies the forecast time step from forecast base time
  step=0,

#Base time
  time=00,

#Specifies the Analysis date, the Forecast base date or Observations date
  date=2013-09-01/to/2013-09-30,

Post Processing Keywords

https://software.ecmwf.int/wiki/display/UDOC/Post-processing+keywords 

#Output grid mesh
  grid=0.75/0.75,

#Area
  area=75/-15/30/42.5,

Data Storage Keywords

https://software.ecmwf.int/wiki/display/UDOC/Data+storage+keywords 

#specifies a Unix file into which data is to be written after retrieval
    target="ei_sfc_165_41.grib",

##OPTIONAL MARS SERVICE KEYWORD
   #(Optional) argument to retrieve NetCDF format
     format=netcdf,

Keywords

You can find all the keyword explanation in our Mars Keywords page.

There is an extra keyword that you can use in Access MARS that does not appear in the MARS Documentation:

Keyworddefinition
formatYou can add format = netcdf to retrieve the data in NetCDF format.