[MITgcm-support] nTimeStep

[smaeilpour]

Thank you Jody,
I restarted with a deltaT=5, that is small as following:

startTime=0,
endTime=86400,
deltaT=5,

but Model after a while (about 1500 of nTimeStep) becomes unstable, what solution else do you offer except that? and what CFL criteria else should i consider for it?

Thank you again,
Saeid



--------------------------------------------
On Wed, 6/7/17, Jody Klymak <jklymak at uvic.ca> wrote:

 Subject: Re: [MITgcm-support] nTimeStep
 To: mitgcm-support at mitgcm.org
 Date: Wednesday, June 7, 2017, 12:26 PM
 
 
 
 9 times out of 10 you will get this if deltaT is too
 large.  Look for advcfl_*_max in
 STDOUT.0000.  They should be less than one, and
 preferably less than 0.5. A couple of things to be aware of
 
 
 setting hFacMin to be too
 small value can mean your vertical cell is very small, and
 the CFL
 condition becomes impossible to meet.  hFacMin
 is the fraction of dR that a cell is allowed to
 be near the bottom, so dR=10 m and 
 hFacMin=0.1 means the cell can be as thin as 1
 m. If your deltaT=50 then W
 can’t exceed 2 cm/s in that cell.  If the topography is
 steep that is not a gigantic value for W near
 topography.you may have strong start-up
 transients in your solution that make the model behave more
 violently at the start than after it has been allowed to
 evolve.  So check STDOUT.0000 and if the CFL
 criteria starts to drop again, you may be able to restart
 with a smaller deltaT.
 
 
 Good luck,  Jody
 
 On 7 Jun 2017, at 8:35,
 smaeilpour wrote:
 
 
 Hi everyone,
 
 I am trying to run Internal wave, my bathymetry file is
 2160*876 and precision 30s. I'd like to run it in 38
 layer and by 3500m depth. The Model with nTimeStep=100 would
 be run well but whenever I increase it for more times I
 encounter with the following error:
 
 
 
 ABNORMAL END: S/R MON_SOLUTION, stops due to EXTREME
 Pot.Temp
 
 
 
 My error in STDER.0000 is:
 
 (PID.TID 0000.0001) SOLUTION IS HEADING OUT OF BOUNDS:
 tMin,tMax=-1.918+101  1.617+101
 
 (PID.TID 0000.0001)  exceeds allowed range
 (monSolutionMaxRange= 1.000E+03)
 
 (PID.TID 0000.0001) MON_SOLUTION: STOPPING CALCULATION at
 Iter=  20
 
 (PID.TID 0000.0001) ***ERROR***S/R ALL_PROC_DIE: ending the
 run
 
 
 
 Of course, once I used startTime and endTime instead of
 nTimeStep but it didn't matter.
 
 
 
 My data file is as following:
 
  nIter0=0,
 
  nTimeSteps=8640,
 
  deltaT=50,
 
  dumpFreq=21600,
 
  pChkptFreq=0,
 
  chkptFreq=0,
 
  monitorFreq=2500.,
 
  periodicExternalForcing=.TRUE.,
 
  externForcingPeriod=2592000.,
 
  externForcingCycle=31104000.,
 
  tauThetaClimRelax=31104000.,
 
  abEps=0.02,
 
  &
 
 
 
 Is it possible that my domain is big for internal wave
 analysis that I get that error? if not so, how can I fix
 this problem? how can I run model for 4 years and more with
 this situation?
 
 
 
 Thank you in advance for any help,
 
 Saeid
 
 
 
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