- Created by Unknown User (nagc) on Oct 24, 2017
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Obtaining initial files
To request start data for OpenIFS, please contact openifs-support@ecmwf.int with the following information:
- Resolution required (e.g. T159, T255, etc)
- Start date(s) (e.g. 2015/11/01 to 2015/11/05)
- Run length
- Data source (ERA-Interim, ERA-5, Operational analyses)
Requests can usually be processed in 24hrs, larger data requests or higher resolution will take 2-3 days.
Unfortunately model changes between the data sources compared to OpenIFS have meant delays to providing user tools for creating start data for OpenIFS. To ensure correctly balanced initial conditions the preferred way of obtaining data to start the model is via openifs-support@ecmwf.int who will respond to reasonable requests quickly.
Initial files
The initial files containing 2D and 3D fields to start the forecast are contained in file that begin with ICM* : ICMGG* are the initial gridpoint files, ICMSH* are the initial spectral fields. ICMCL* is the file containing the climatological forcing fields.
The experiment id is contained the names of the initial files, and it is encoded into the GRIB messages within those files.
Use the 'grib_ls' command to examine the initial files:
grib_ls ICMGGob00INIT grib_ls ICMSHob00INIT
OpenIFS namelist
The file: fort.4 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.
The wave model, WAM, also has a separate namelist.
OpenIFS experiments
An 'experiment' is created for OpenIFS forecast initial data. An experiment identifier, or 'id', is a 4 character sequence, embedded in the initial data filename and as a GRIB key in the headers of each file. For example, ICMSHg8ddINIT, would be the file for the initial spectral fields ('SH'), for the experiment labelled 'g8dd'.
An experiment can be a single forecast date or a combination of multiple dates. Each date could be a single forecast or a ensemble of forecasts from a single date. But each experiment will use the same model resolution. For example, an experiment comprising a 5 member ensemble with 5 start dates (say 1st-5h December 2015) would result in 25 separate model forecasts.
Listing the experiment id
The command 'exptid' can be used to check and change the experiment id in the GRIB files.
> exptid ICMSHob00INIT In file ICMSHob00INIT, values of key experimentVersionNumber are: ob00
The 'experimentVersionNumber' is the GRIB parameter encoded in the GRIB fields.
This can also be seen using the 'grib_ls' command to list the contents of the file:
> grib_ls -p shortName,typeOfLevel,dataDate,experimentVersionNumber ICMSHob00INIT ICMSHob00INIT shortName typeOfLevel dataDate experimentVersionNumber t hybrid 20151101 ob00 t hybrid 20151101 ob00 t hybrid 20151101 ob00 .......
The 'exptid'
and 'grib_ls'
commands can also be used for multiple files:
troifs0@cca-login3:> exptid ICM* In file ICMCLob00INIT, values of key experimentVersionNumber are: 0001 In file ICMGGob00INIT, values of key experimentVersionNumber are: 0001 ob00 In file ICMGGob00INIUA, values of key experimentVersionNumber are: ob00 In file ICMSHob00INIT, values of key experimentVersionNumber are: ob00
Note that the ICMCL and ICMGG*INIT files both have a experimentVersionNumber key of '0001'. This is used for climatological fields.
Changing the experiment id
All experiments with OpenIFS should use a 4-character experiment id. At ECMWF, these ids are assigned by the system. However, OpenIFS users have the freedom to change the experiment id if they choose to.
A command is available with OpenIFS to change the experiment id in the 'bin' directory of the OpenIFS distribution.
Changing experiment id requires changes to the GRIB headers in the file, not just the filename itself.
> exptid -n ob01 ICM*ob00* Changing expid from 'ob00' to 'ob01' for ICMCLob00INIT and writing to new file ICMCLob01INIT. Changing expid from 'ob00' to 'ob01' for ICMGGob00INIT and writing to new file ICMGGob01INIT. Changing expid from 'ob00' to 'ob01' for ICMGGob00INIUA and writing to new file ICMGGob01INIUA. Changing expid from 'ob00' to 'ob01' for ICMSHob00INIT and writing to new file ICMSHob01INIT.
Available initial dates
A number of initial dates are already available.
Due to space constraints, it is not possible to provide these all via ftp. If you would like a copy of any of these files, please contact openifs-support@ecmwf.int.
Expt id | Dates | Resolutions | Event / Remarks |
---|---|---|---|
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