[MITgcm-support] non-periodic forcing files

[Quentin Jamet]

Dear MITgcm users,

I have made some modifications in the code to force a model with forcing 
files that are made as sub-samples (in time) of longer time series. This 
avoid the use of too large forcing files, and, I think, speeds up the 
reading, which becomes interesting when the model is integrated on a 
platform with a time limit. It might be of interest for some of you.

The idea is to use periodicExternalForcing=.TRUE., and to modify the 
interpolation in time made at the beginning and at the end of a cycle. 
Then, externForcingCycle corresponds now to the length of a sub-sample, 
and externForcingPeriod is the usual time step between time records. 
Instead of interpolating data between the last and the first time record 
at the beginning and at the end of a cycle, the interpolation is now 
made between the third last and the second last time record at the end 
of a cycle, and between the last and the first time record at the 
beginning of a cycle. This is made by setting useYearlyField=.TRUE. in 
data, &PARM03. Forcing files have to be extended accordingly, with 2 
additional time records placed at the end, the last (second last) 
corresponding to the last (first) time record of the preceding 
(following) cycle.

These modifications are made in get_periodic_interval.F, where two 
global model parameters are added as input: nIter0 and useYearlyField.
- nIter0 is used to discriminate if the interpolation is made between 
the last and the first time record at the very first model time step 
within a cycle, or between the third last and the second last time 
record at the very last model time step within a cycle.
- useYearlyField (defined in PARAMS.h, and set by default to .FALSE. in 
set_defaults.F) allows to switch from periodic to non-periodic 
(sub-sampled) forcing files.
All files that CALL GET_PERIODIC_INTERVAL have to be modified 
accordingly. A specific flag 'useYearlyField_xxx' can be defined for 
each package.

Modified files are available here: 
http://ocean.fsu.edu/~qjamet/data/yearlyForcing/code/

Feel free to comment/update/share.

Best,

Quentin




-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.mitgcm.org/pipermail/mitgcm-support/attachments/20170925/775fb70e/attachment.html>