[MITgcm-support] Deviated results after restart

[Weiyang Bao]

Dear all,

I’m running a simulation for a freshwater-discharged coastal channel. The model is run with multi processors and it could restart from the pickup files and end normally without reporting any error. However, the output results (T, S, U) become different from those at the same timestep in a non-restart run, after initial conditions being loaded correctly from the pickup. That is to say, the 1st-iteration output in the restart is identical to the same-realtime output in a non-restart run but consequent results begin to differ. A plot showing the divergence at one grid point is attached here:




The data file I used is as follow:

 &PARM01
 tRef=90*0.,
 sRef=90*34.,
 viscAz=0.00001,
 viscC2smag=2.2,
 diffKzT=0.00001,
 diffKhT=20,
 diffKzS=0.00001,
 diffKhS=20,
 bottomDragQuadratic=2.5E-3,
 implicitViscosity=.TRUE.,
 implicitDiffusion=.TRUE.,
 no_slip_sides=.FALSE.,
 no_slip_bottom=.TRUE.,
 rigidLid=.FALSE.,
 implicitFreeSurface=.TRUE.,
 hFacMin=0.05,
 readBinaryPrec=64,
 staggerTimeStep=.TRUE.,
 tempAdvScheme=33,
 saltAdvScheme=33,
 eosType='JMD95Z',
 f0=1.2E-4,
 beta=0.E-11,
 selectAddFluid=1.,
 useSingleCpuIO=.TRUE.,
 &

# Elliptic solver parameters
 &PARM02
 cg2dMaxIters=300,
 cg2dTargetResidual=1.E-13,
 cg3dMaxIters=20,
 cg3dTargetResidual=1.E-8,
 &

# Time stepping parameters
 &PARM03
 nIter0=0,
 endTime=20000.,
 deltaT=2.,
 abEps=0.01,
 pChkptFreq=1000.,
 chkptFreq=0.,
 pickupSuff='',
 dumpFreq=1000.,
 monitorSelect=1,
 monitorFreq=1000.,
 periodicExternalForcing=.FALSE.,
 &

# Gridding parameters
 &PARM04
 usingCartesianGrid=.TRUE.,
 delXfile='delx.bin',
 delYfile='dely.bin',
 delZ= 20*2,30*4,40*6.,
 &

# Input datasets
 &PARM05
 bathyFile='bathymetry.bin',
 hydrogThetaFile='tempini.bin',
 hydrogSaltFile ='saltini.bin',
 &

I only modified nIter0 every time before restart, is there anything else needs attention? Thanks a lot for your time!

Best, Weiyang
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