[MITgcm-devel] Identical executable producing diverging results

[An T Nguyen]

Hi all,

I wasn't sure where I should send this email, but I'm hoping someone could help me with this issue:

I ran 2 experiments (one @ 18km and one @ 9km resolution) back in June 2009, and now am repeating
the exact experiments.  The results are diverging, and in 1 case the model crashes in 2002 while the
original experiment ran to 2009 without any problem.  The divergence is true for both 18km and 9km
runs, and the first place it diverges is at exf_hflux_max/min/mean/sd/del2 and
exf_sflux_max/min/mean/sd/del2 at time-step 0 in the STDOUT file.

I include here the beginning of two 9-km STDOUT files, one of the original run back in June, and one
of this month run.  All input files are identical.  Forcing files and executables (mitgcmuv) are 
also identical.  The locations of these 2 runs are:

Original:
cfe2:/nobackup2a/menemenl/arctic/arctic_9km/MITgcm/exe_firstrun_1992_2009/

Repeat:
cfe2:/nobackup1/atnguyen/arctic/MITgcm/exe_firstrun_1992_2009

The 18km runs also differ at the same place.  Could this be due to some changes on the Columbia side?

I also notice that if I repeat the same experiments from pick-up files that were generated after Jun 
27, 2009, then I get exact results.  So it seems that results generated prior to approximately this 
date can not be repeated.

Thanks,
An


-- 
An T. Nguyen, Ph.D. <atn at jpl.nasa.gov>
Jet Propulsion Lab, California Institute of Technology
MS 300-323, 4800 Oak Grove Dr, Pasadena CA 91109-8099
tel: 818-354-4122; fax: 818-393-6720
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