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Table of Contents

Introduction

This is a brief introduction of the main request parameter syntax of MARS. For further information/features, please refer to: Request syntax.

Note

We recommend that you get familiar with datasets and their availability using http://apps.ecmwf.int/datasets/

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

...

Syntax

Code Block
languagebash
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 tempreraturetemperature

Retrieve example from "View MARS request":


Code Block
titleMARS request
retrieve,

...

stream=oper,
 levtype=

...

sfc,
 param=165.128/41.128,

...

dataset=interim,
 step=

...

0,
 grid=0.75/0.75,

...

time=

...

00,
 date

...

=2013-09-01/to/2013-09-30,

...

type=an,
 class=

...

ei



Code Block
languagepy
titlePython equivalence
 #!/usr/bin/env python
from ecmwfapi import ECMWFDataServer
   
server = ECMWFDataServer()
   
server.retrieve({
    'dataset' : "interim",
	'time'    : "00",
	'date'    : "2013-09-01/to/2013-09-30",
    'step'    : "0",
    'type'    : "an",
    'levtype' : "sfc",    
    'param'   : "165.128/41.128",
    'grid'    : "0.75/0.75",
    'target'  : "interim201309.grib"
    })


Keyword

In the Dataset service there is an extra mandatory keyword called dataset which does not appear in normal MARS requests.

Keyworddefinition
dataset See Available Datasets
formatYou can add 'format' : "netcdf" to retrieve the data in NetCDF format.

the other possible MARS keywords are explained in the MARS keywords documentation.

Keyword exaplanation:

...

ECMWF classification to the given data:

  • Operations (od)
  • Research experiments (rd)
  • Re-Analysis datasets (e4 for ERA-40, er for ERA-15)
  • European Climate Network Support (cs)
  • DEMETER project (dm)

...

Identifies the forecasting system used to generated the data when the same meteorological types are
archived.
  • oper is used for the Operational Atmospheric model
  • wave for the Wave model
Both models produce Analysis and Forecast data types.

...

Base time (00, 06, 12 and 18)

Observation time (HHMM or HH:MM: ie 09:30)

...

Specifies the Analysis date, the Forecast base date or Observations date. Formats

  • Absolute as YYYY-MM-DD, YYYYMMDD. The day of the year can also be used: YYYY-DDD
  • Relative as -n ; n is the number of days before today (i.e., -1 = yesterday )
  • Name of month (e.g. january for Climatology data)
  • Operational monthly means are retrieved by setting day (DD) to 00.

...

Determines the type of field to be retrieved:

This keyword makes the selection between observations, images or fields, and it determines some of the valid remaining keywords of the request.
  • Analysis (an)
  • Forecast (fc)
  • Perturbed Forecast (pf)
  • Control Forecast (cf)

...

Denotes type of level:

  • Model level (ml)
  • Pressure level (pl)
  • Surface (sfc)
  • Potential vorticity (pv)
  • Potential temperature (pt)
  • Depth (dp)

...

Meteorological parameter. (t, temprerature, 130, 30.128, ...)

...

specifies a Unix file into which data is to be written after retrieval or manipulation. Path names should always be enclosed in double quotes:

...