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WPS Input Data With Varying Time Intervals


New member
Hi, I want to do a 10 days forecast, and run the WRF by initialising it with ECMWF boundary conditions.
The ECMWF files are in grib format but they don't have the same time interval for all the files for 10 days forecast files.

The Input files (ECMWF grib files) are available in a progressive time interval - 1hr up to 90 hours, then 3 hours up to 150 hours, then 6 hours up to 240 hours (10 days).

So, I want to know how to set up my WPS namelist file? as I believe we can only put a single value for interval_seconds field in the namelist.wps file.
do I need to run WPS separately for each time interval? if so then how would I run the real.exe as we also need to mention input file interval_seconds in the WRF namelist.input file?

Can you please help and advise on this issue?


Staff member
Apologies for my confusion, but I don't understand what you mean by the different times for the input data. Are there some files that are hourly, but they only go out to a 90 hour forecast, some that are 3-hourly, but only go out to a 150 hour forecast, and then some that are 6-hourly and go all the way out to a 240 hour forecast? If this is the case, then since you want to run for 10 full days, you will need to use the 6-hourly forecast data.

If that is not the correct interpretation, can you provide some example data files so I can take a look? If the files are too large to attach here, take a look at the home page of this forum for instructions on sharing large files.


New member
Hi, Yes you understand correctly.

I suppose I could use the option of restarting the WRF simulation.
First, run for 150 hours with 3-hour files, then from 150 to 240 hours with 6-hour files. then combine the 2 WRF output files.

can this arrangement considered as the whole 10-day run (single forecast)?

Also, can you please tell me while setting up the namelist file?
first run - restart_interval = 9000, restart = .false.,
when I am doing the second run what should I set the value for "restart_interval", ? with restart = .false.,

Ming Chen

Staff member
I believe you can specify time interval based on your need. Note that ungrib has the capability to interpolate data. For example, if you have data at 00 and 12 UTC, but your time_interval = 21600. Then ungribn will extract data at 00 and 12 UTC, and interpolate the data to 06 UTC. As a result, you will have intermediate files at 00, 06 and 12 UTC.