time split of forcing file

Discussion of how to use ROMS on different regional and basin scale applications.

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jalves

time split of forcing file

#1 Post by jalves » Wed Oct 10, 2007 10:08 am

Is it possible to create various forcing files for the same variable and run ?
For instance I would like to create 3 wind forcing files for periods of 10 years to do a 30 years run .

Thanks in advance,
jalves

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kate
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#2 Post by kate » Wed Oct 10, 2007 5:56 pm

Yes, you can. However, you will want to duplicate at least one record from consecutive files. For instance, if you have monthly winds, you will want to have January for year 11 on the end of your first file. Then you can run to Jan 15 (if they are middle of the month) using the first file, then restart using the second file. Warning: there have been ROMS versions which silently ran past the end of their forcing file without complaint.

The winds I'm using now are yearly files with 6-hourly values and Liz Dobbins duplicated the whole of January. It means we have to switch from one to the next sometime during that month each year.

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#3 Post by arango » Thu Oct 11, 2007 4:29 pm

No, you cannot have a continous 30 year run with foricng split on three 10-year files. This requires substantial change to ROMS IO strategy. We do not want to do such thing because it breaks the adjoint IO logic. What you can do is cycle forcing every 10 years or save each forcing field in different NetCDF but for the full 30 years.

The issue here is that all the IO in ROMS has a very complex initialization and this is only done once, at initialization when all the NetCDF files are open and the clocks are initialized. It will be tricky to restart this internal initialization at different times.

However, you can do this by restarting every 10 years. Recall that now ROMS has a perfect restart.

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