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The following MARS requests can be used as a tutorial. The links into the MARS Catalogue might be helpful to create a valid retrieve script. However, the dates might need to be adapted.

As one can very easily retrieve large amounts of data it is best to start mars in a location where plenty of disk space is available, e.g. in $SCRATCH:

cd $SCRATCH

The solutions below provide valid MARS requests which can be passed to the mars command as

% mars < myrequestfile
                             or
% mars myrequestfile

Simple retrieves

Retrieve 1000,850,700 and 500 hPa temperatures from the 15th of February 1999 12 UTC Analysis  > see in MARS Catalogue 

 solution
retrieve,
    class    = od,
    type     = an, 
    expver   = 1,
    date     = 19990215,
    time     = 12,
    param    = t, 
    levtype  = pressure level,
    levelist = 1000/850/700/500,
    target   = "t.grb"

Retrieve wind components for tomorrow at 12:00 and 18:00 from yesterday's 12Z forecast at all 137 model levels  > see in MARS Catalogue

 solution
retrieve,
    type     = forecast, 
    param    = u/v, 
    levtype  = model level,
    levelist = 1/to/137,
    date     = -1,
    time     = 12,
    step     = 48/54, 
    target   = "wind"

Retrieve geopotential and surface pressure for yesterday's analysis cycles (00,06,12,18)  > see in MARS Catalogue

 solution
retrieve,
    class   = od,
    type    = analysis,
    levtype = surface,
    date    = -1,
    time    = 00/06/12/18,
    param   = z/sp,
    target  = "all.an"

Retrieve surface pressure and surface thermal radiation downwards at every 12-hour time-step for the 12Z forecast from two days ago  > see in MARS Catalogue

 solution
retrieve,
    type    = forecast,
    param   = sp/str,
    date    = -2,
    step    = 12/to/240/by/12,
    time    = 12,
    levtype = sfc,
    target  = "sfc.grb"

Retrieve the operational monthly mean model level temperature (all levels) from the 06:00 analysis for February 1997  > see in MARS Catalogue

 solution
retrieve,
    class    = od,
    stream   = mnth,
    type     = analysis,
    time     = 06,
    date     = 19970200,
    levtype  = model level,
    param    = t,
    levelist = 1/to/31, 
    target   = "monthly"

Retrieve the temperature on model levels 1, 2 and 3 for yesterday's 12 hour forecast. > see in MARS Catalogue

 solution
retrieve,
    type    = fc,
    date    = -1,
    time    = 12,
    step    = 12,
    levtype = ml,
    level   = 1/2/3,
    param   = t,
    target  = "t_ml_1_2_3"

Time and step

Retrieve the 1000 hPa geopotential from yesterday's 12 UTC forecast (> see in MARS Catalogue) for:

  • the 12 hour forecast

     solution
    retrieve,
        type    = fc,
        date    = -1,
        time    = 12,
        step    = 12,
        levtype = pl,
        level   = 1000,
        param   = z,
        target  = "z1000_a"
    
  • the 6, 12, 24 and 48 hour forecasts

     solution
    retrieve,
        type    = fc,
        date    = -1,
        time    = 12,
        step    = 6/12/24/48,
        levtype = pl,
        level   = 1000,
        param   = z,
        target  = "z1000_b"
  • the 12 hour to 240 hour forecasts at 12 hour intervals

     solution
    retrieve,
        type    = fc,
        date    = -1,
        time    = 12,
        step    = 12/to/240/by/12,
        levtype = pl,
        level   = 1000,
        param   = z,
        target  = "z1000_c"
    
  • all forecast time-steps

     solution
    retrieve,
        type    = fc,
        date    = -1,
        time    = 12,
    #   step    = all, # The value "all" is convenient to use but MARS can only report on missing steps if 
    # the full list of steps is specified:
    step = 0/1/2/3/4/5/6/7/8/9/10/11/12/13/14/15/16/17/18/19/20/21/22/23/24/25/26/27/28/29/30/31/32/33/34/35/36/37/38/39/40/41/42/43/44/45/46/47/48/49/50/51/52/53/54/55/56/57/58/59/60/61/62/63/64/65/66/67/68/69/70/71/72/73/74/75/76/77/78/79/80/81/82/83/84/85/86/87/88/89/90/93/96/99/102/105/108/111/114/117/120/123/126/129/132/135/138/141/144/150/156/162/168/174/180/186/192/198/204/210/216/222/228/234/240,
    levtype = pl, level = 1000, param = z, target = "z1000_d"

ENS Overlap

Retrieve Total Precipitation, perturbed forecast overlap

 solution

RETRIEVE,
  STREAM  = EFOV,
  CLASS   = OD,
  DATE    = -1,
  TIME    = 00/12,
  EXPVER  = 1,
  STEP    = 240,
  TYPE    = PF,
  NUMBER  = 1/TO/50
  LEVTYPE = SFC,
  PARAM   = TPVAR,
  TARGET  = TP_EFOV

See also FAQ: "How can I compute the accumulation using data from the overlap stream?"

Post-processing

Retrieve the 1000,500 and 300 hPa temperatures for today at noon from the 12 UTC forecast of two days ago on an N48 Gaussian Grid  > see in MARS Catalogue

 solution
retrieve, 
    type     = forecast, 
    param    = t, 
    date     = -2,
    time     = 12, 
    step     = 48, 
    grid     = N48, 
    levelist = 1000/500/300, 
    levtype  = pl, 
    target   = "t.gg.grb"

Retrieve the same on a latitude/longitude grid, 1.5 by 1.5 degrees. > see in MARS Catalogue

 solution
retrieve, 
    type     = forecast,
    param    = t,
    date     = -2,
    time     = 12,
    levelist = 1000/500/300,
    levtype  = pl,
    step     = 48,
    grid     = 1.5/1.5,
    target   = "t.ll.grb"

Retrieve Europe in the same way as in the previous retrieval. Compare the size of the resulting file with the previous one. > see in MARS Catalogue

 solution
retrieve,
    type     = fc,
    param    = t,
    date     = -2,
    time     = 12,
    levelist = 1000/500/300,
    levtype  = pl,
    step     = 48,
    grid     = 1.5/1.5,
    area     = e,
    target   = "t.europe"

Retrieve the 1000 and 500 hPa geopotential for 1200 yesterday from the analysis in the formats below (one job for each form): > see in MARS Catalogue

  • leaving the data in its original form

     solution
    retrieve,
        type    = an,
        date    = -1,
        time    = 12,
        param   = z, 
        levtype = pressure level,
        level   = 1000/500,
        target  = "myfile1"
  • reducing the truncation to T106

     solution
    retrieve,
        type    = an,
        date    = -1,
        time    = 12,
        param   = z, 
        levtype = pressure level,
        level   = 1000/500,
        resol   = 106,
        target  = "myfile1"
  • converting the data to a global N48 Gaussian grid

     solution
    retrieve,
        type    = an,
        date    = -1,
        param   = z, 
        levtype = pressure level,
        level   = 1000/500,
        grid    = N48,
        target  = "myfile1"
  • converting the data to a regular 5.0 by 5.0 degree global latitude/longitude grid

     solution
    retrieve,
        type    = an,
        date    = -1,
        param   = z, 
        levtype = pressure level,
        level   = 1000/500,
        grid    = 5.0/5.0,
        target  = "myfile1"
  • converting the data to an N80 Gaussian grid for the European area

     solution
    retrieve,
        type    = an,
        date    = -1,
        param   = z, 
        levtype = pressure level,
        level   = 1000/500,
        grid    = N80,
        area    = europe,
        target  = "myfile1"
  • converting the data to an N80 Gaussian grid for the area from 50 degrees North to 10 degrees North, and 20 degrees West to 20 degrees East

     solution
    retrieve,
        type    = an,
        date    = -1,
        param   = z, 
        levtype = pressure level,
        level   = 1000/500,
        grid    = N80,
        area    = 50/-20/10/20,
        target  = "myfile1"
  • converting the data to the same area but convert it to a 2.5 degree by 2.5 degree latitude/longitude grid

     solution
    retrieve,
        type    = an,
        date    = -1,
        param   = z, 
        levtype = pressure level,
        level   = 1000/500,
        grid    = 2.5/2.5,
        area    = 50/-20/10/20,
        target  = "myfile1"
    

Retrieve surface winds for yesterday's 24 hour forecast on the European area converting to a 0.57 by 0.57 degrees latitude/longitude grid. > see in MARS Catalogue
What happens to the conversion?

 solution
retrieve,
    type    = fc,
    date    = -1,
    time    = 12,
    step    = 24,
    levtype = sfc,
    param   = 10u/10v,
    area    = europe,       # As the area is not compatible with the grid,
    grid    = 0.57/0.57,    # MARS will expand the area to make it fit.
    target  = "10u_10v"

 

Observations

Retrieve all the sea surface observations for the 1st February 2015.  > see in MARS Catalogue

 solution
retrieve, 
    type    = ob, 
obsgroup= con, obstype = ssd, date = 20150201, time = 00, range = 1439, target = "obs.bufr"

Ensemble forecasts

Retrieve the surface temperature fields of the first 10 members of yesterday's 12 UTC ensemble prediction (type: perturbed forecast) for the next 3 days at noon. > see in MARS Catalogue

 solution
retrieve,
    class    = od,
    stream   = ef,
    type     = perturbed forecast,
    levtype  = sfc,
    repres   = gg,
    date     = -1,
    time     = 12,
    ensemble = 1/to/10,
    step     = 48/to/96/by/24,
    param    = st,
    target   = "ensemble"

Retrieve the same for the control forecast. > see in MARS Catalogue

 solution
retrieve,
    class   = od,
    stream  = ef,
    type    = control forecast,
    levtype = sfc,
    repres  = gg,
    date    = -1,
    time    = 12,
    step    = 48/to/96/by/24,
    param   = st,
    target  = "ensemble.cf"

ERA 40

Retrieve the vertical integral of eastward and northward heat flux as monthly means of daily means on a 1.125 by 1.125 degree latitude/longitude grid over Europe from the ERA 40 archive for January 1964 > see in MARS Catalogue

 solution
retrieve,
    class   = e4,
    stream  = moda,
    type    = an,
    levtype = sfc,
    date    = 19640101,
    param   = 69.162/70.162,
    area    = europe,
    grid    = 1.125/1.125,
    target  = "e4_moda_fluxes.grb"

Retrieval of snow depth from the ERA-40 archive for November 1993, for all analysis base times > see in MARS Catalogue. How many fields are requested?

 solution
retrieve,
  class   = e4,
  stream  = oper,
  expver  = 1,
  date    = 19931101/to/19931130,
  time    = 00/06/12/18,
  type    = an,
  levtype = sfc, 
  param   = sd,
  repres  = gg,
  target  = "era40.199311.sd"
#                                  It retrieves 30 x 4 = 120 fields.

 

See also these Web API retrieve examples for ERA-Interim, S2S, TIGGE, ERA-20C etc.