[MITgcm-support] Question about bin files

[Jody Klymak]

Hi Xing,

> I’m having a question about bin files as initial conditions. I’m trying to write my own initial S and T files for tutorial_global_oce_latlon, so I read lev_s.bin first and tried to see how it looks. I think it should be having a size of 90x40x15=54000. However, its size is 2592000, which equals to 90x40x15x48.

My version of that tutorial is 45x40x15 = 27000.  The size of lev_s.bin is 2592000 *bytes*.  At 8 bytes (64 bits) per value, thats 2592000/8 = 324000 elements, which is 12 times larger than your domain. 

You will note in `data` that

# 2 months restoring timescale for temperature
 tauThetaClimRelax=  5184000.,
# 6 months restoring timescale for salinity
 tauSaltClimRelax = 15552000.,
 periodicExternalForcing=.TRUE.,
# 30 d
 externForcingPeriod=2592000.,
# 360 d
 externForcingCycle=31104000.,

So the factor of 12 is for the monthly (ahem 30-d) climatology of theta and salt.  ie the files are nt*nz*ny*nx.  The model will try and force itself back to these values with a time scale of 2 months for temperature, and 6 months for salt.

Someone will correct me if I have this wrong, but I think its correct.

I was going to simply suggest reading the manual, but this is not super-clearly documented that I could see either in the tutorial or in the main body of the docs.  In fact, I wasn’t aware you could do relaxation to climatology this way, and would have used the `rbcs` package to do the same thing.

Cheers,   Jody


> I’m not sure what does that 48 represent. I also tried to read lev_sss.bin and hoping its size is 90x40=3600 but instead it has a size of 172800=90x40x48. I think I must missed something. Does anyone know how to interpret the sizes of those bin files?
> 
> Thanks!
> Xing
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