Login to ECMWF Cray

Each participant will have a training user account on the ECMWF Cray system. This is different from the user account on the classroom computers.

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This is the directory in which we will run OpenIFS.

Creating the OpenIFS ensemble experiment

An ensemble experiment consists of a 'control' and multiple 'perturbed' forecasts, or 'ensemble members'. For the operational ECMWF ensemble forecast, 50 members are used.

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The exercises show how to create the experiment directories, prepare the jobs and submit them to the ECMWF Cray.

createENS command

Use the command createENS to create the ensemble experiment:

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createENS --help

usage: createENS [-h] -d <startdate/enddate/hr_inc> [-m <members>]
Set up ensemble forecast for the OpenIFS 2015 workshop
optional arguments:
  -h, --help            show this help message and exit
  -d <startdate/enddate/hr_inc>, --date <startdate/enddate/hr_inc>
                        List of date(s) to retrieve, format: YYYYMMDDHH. The
                        only dates available are: 2013102400/2013102700/24
  -m <members>, --members <members>
                        Number of ensemble members to create e.g. 3 (default 1)

Exercise

Change to the experiment directory labelled by the date chosen:

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Understand what the different files in the experiment directory are for.

Initial files

ICM* : these are the initial starting files. ICMGG* are the initial gridpoint files, ICMSH* are the initial spectral fields.

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grib_ls ICMGGoifsINIT
grib_ls ICMSHoifsINIT

Fortran namelist

The file: namelistfc is the model 'NAMELIST'. It contains a list of variable settings or 'switches' that control what the model does. These variables are grouped into separate fortran namelists.

The model will read this file when it starts up. There are many options to control the model. For more information, it is best and recommended to check the comments in the code. Please ask if you are interested.

Creating the OpenIFS namelist

Set the ensemble member

In IFS, each ensemble member uses the stochastic physics schemes to generate uncertainty. A random number 'seed' is used by the stochastic scheme to generate a different forecast. This random number seed is changed by altering the ensemble member value in the model's namelist. Each ensemble member must have a unique number and therefore random number seed, in order to produce a different forecast.

Exercise

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Create and submit Cray batch job

The next steps are to create and submit a batch job to run on the ECMWF Cray XC30 system.

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Exercise

Use the oifs_run command to create the job.

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These are the model output files. There is 1 per output interval. In these experiments the output interval is every 3 hours.

Checking the model output

After the qstatu command shows that the job has completed, there will be a 'batch log file' in the pf001 directory:

oifs_troifs1.o1481792

Exercise

Using your favourite text editor, check this file to make sure the model has run correctly.  It's usually best to start from the bottom of the file and scroll up.

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Preparing files for Metview

The next step is to take the output of the successful run and prepare it for the Metview based exercises.

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