Hi Peter, I am responding to this via the mom4-bulletin board to solicit input from others.
The short answer is: I do not know. The long answer is that in mom4, we have what we call a "regression test suite". In this suite, we test the code using some basic comp-sci sorts of metrics (amongst others). An important metric that we insist upon is reproducibility across restarts and reproducibility across numbers of processors. An example is 1day on x-pes + 1day on y-pes = 2days on z-pes mom4 code that is sanctioned satisfies this test on our machines (SGIs). We cannot guarantee that it does on others, and there are examples where others have reproducibility problems (typically a compiler issue). When developing mom3, we did similar regression tests, so at least at GFDL we have not seen behaviour as you account below. Perhaps the mom-community can chime-in with accounts like yours...(ANYONE??) -Steve Dr Peter Killworth wrote: > > Steve, pass this on to whomever... > I've been testing a very benign eddy parameterisation on our 24-processor > machine here that GFDL helped get MOM3 working on. > I find that if I start the global (and vanilla) run from scratch, and (say) > run for 2 years, dumping every year, things are fine. I can take the restart, > shift it into restart.dta or whatever it's called, and run another 2 years. > And so on. Got it to 10 years with no problem. > At this stage the restart file got lost (no backup, short of disc space). > Started again asking for a 20-year run, dumping every 2 years. > Even the first dump was NaNs. > I am beginning to think it's the SGI somehow. Others have had similar > effects. Different answers on different days. > Query: > have you had any reports of mom3 giving different answers depending on how > it's started, machine it's on, etc.? > (It may just be me, of course.) > Peter -- Dr. Stephen M. Griffies phone: +1-609-452-6672 Geophysical Fluid Dynamics Laboratory FAX: +1-609-987-5063 P.O. Box 308, Forrestal Campus Site B email: [EMAIL PROTECTED] Princeton, NJ 08542 USA http://www.gfdl.noaa.gov ------------------------------------------------------- This SF.net email is sponsored by: eBay Get office equipment for less on eBay! http://adfarm.mediaplex.com/ad/ck/711-11697-6916-5 _______________________________________________ FMS-mom4 mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/fms-mom4
