[MITgcm-support] NaNs in output

[Yuan Lian]

I think the model runs global simulation in cube sphere grid, so no delX and  
delY are defined. 

It looks like the model runs unstable. What are the CFL values before NaNs  
appear? Dose the temperature field look  suspicious too?

Yuan

-----Original message-----
From: Martin Losch <Martin.Losch at awi.de>
To: mitgcm-support at mitgcm.org
Sent: Sun, Sep 30, 2012 23:40:02 PDT
Subject: Re: [MITgcm-support] NaNs in output

The model becomes numerically unstable (and this can happen after some time,  
if the forcing is variable) and you need to investigate your input  
parameters (time step, forcing etc.).

I am surprised it runs at all. What is your grid resolution? There is no  
dx/ySpacing or delX/delY in your PARM04 namelist.
It is also strange that your cg2d: line has zeros for the rhsMax.

Martin

On Oct 1, 2012, at 8:01 AM, Fengchao Yao wrote:

> Dear all,
> 
> The MITgcm I am running is constantly giving NaNs after a couple years of  
stable running.  Below is the information from the STDOUT file where the  
NaNs occur. Anybody has some idea on how to handle this? Thanks for your  
help.
> 
> Fengchao
> 
> STDOUT:
>  
----------------------------------------------------------------------------- 
---------------------------------
> cg2d: Sum(rhs),rhsMax =   7.95491814529655E+03  0.00000000000000E+00
> cg2d: Sum(rhs),rhsMax =   7.95490803828502E+03  0.00000000000000E+00
> SURF_ADJUSTMENT: Iter=   3348930 Nb_pts,Vol=         1  7.60072406E+06
> cg2d: Sum(rhs),rhsMax =   7.95489793127349E+03  0.00000000000000E+00
> SURF_ADJUSTMENT: Iter=   3348931 Nb_pts,Vol=         5  1.96015022E+08
> cg2d: Sum(rhs),rhsMax =  -1.77088743107612E+21  0.00000000000000E+00
> SURF_ADJUSTMENT: Iter=   3348932 Nb_pts,Vol=    128878  6.73412758E+43
> cg2d: Sum(rhs),rhsMax =                    NAN  0.00000000000000E+00
> cg2d: Sum(rhs),rhsMax =                    NAN                   NAN
> cg2d: Sum(rhs),rhsMax =                    NAN                   NAN
> cg2d: Sum(rhs),rhsMax =                    NAN                   NAN
> cg2d: Sum(rhs),rhsMax =                    NAN                   NAN
> cg2d: Sum(rhs),rhsMax =                    NAN                   NAN
> cg2d: Sum(rhs),rhsMax =                    NAN                   NAN
> cg2d: Sum(rhs),rhsMax =                    NAN                   NAN
> 
> 
> data file
>  
----------------------------------------------------------------------------- 
--------------------------------
> &PARM01
> tRef               =  
3*23.,3*22.,21.,2*20.,19.,2*18.,17.,2*16.,15.,14.,13.,
>                      12.,11.,2*9.,8.,7.,6.,
> sRef               = 25*38,
> no_slip_sides=.FALSE.,
> no_slip_bottom=.TRUE.,
> 
> viscAh = 3.0e1,
> 
> viscA4 = 0e7,
> viscAhGrid = 0.00,
> 
> viscA4Grid = 0.03,
> 
> viscAr = 7.E-4,
> 
> diffK4T=0e7,
> diffK4S=0e7,
> diffKrT=1.E-5,
> diffKrS=1.E-5,
> diffKrBL79surf=0.1E-4,
> diffKrBL79deep=1.0E-4,
> bottomDragQuadratic= 0.002,
> implicitDiffusion=.TRUE.,
> implicitViscosity=.TRUE.,
> gravity=9.81,
> rhonil=1029.,
> rhoConstFresh=1000.,
> eosType='JMD95Z',
> staggerTimeStep=.TRUE.,
> vectorInvariantMomentum=.TRUE.,
> useEnergyConservingCoriolis=.true.,
> implicitFreeSurface=.TRUE.,
> exactConserv=.TRUE.,
> useSingleCpuIO=.TRUE.,
> tempAdvScheme=30,
> saltAdvScheme=30,
> nonlinFreeSurf=1,
> useRealFreshWaterFlux=.FALSE.,
> allowFreezing=.false.,
> hFacMin=.3,
> hFacMinDr=30.,
> readBinaryPrec=64,
> /
> &PARM02
> cg2dMaxIters=5000,
> cg2dTargetResWunit=1.E-11,
> /
> &PARM03
> nIter0=_stTIME_,
> nTimeSteps=_nsteps_,
> deltaT = _delt_,
> pickupStrictlyMatch=.FALSE.,
> cAdjFreq=0.,
> abEps = 0.01,
> forcing_In_AB=.FALSE.,
> pChkptFreq=31104000.0,
> chkptFreq=31104000.0,
> taveFreq=259200.0,
> periodicExternalForcing=.FALSE.
> #dumpFreq=3600.,
> monitorFreq=2635200000.,
> # tauThetaClimRelax= 2592000.,
> # tauSaltClimRelax= 7776000.,
> /
> &PARM04
> usingCurvilinearGrid=.TRUE.,
> delR= 10.2652, 11.8262, 13.6398, 15.7495, 18.2060, 21.0677, 24.4002,
> 28.2749, 32.7643, 37.9348, 43.8340, 50.4735, 57.8103, 65.7382,
> 74.1055, 82.7805, 91.7766,101.4306,112.6418,127.2439,148.7415,
> 183.8161,244.2570,340.5531,442.0510,
> /
> &PARM05
> bathyFile='redsea_bathy_fixed.bin',
> # bathyFile='red2_bathyed-10.bin',
> hydrogThetaFile='lev01_temp.bin',
> hydrogSaltFile='lev01_salt.bin',
> zonalWindFile ='uf_198002.data',
> meridWindFile='vf_198002.data',
> surfQFile='qf_198002.data',
> EmPmRFile='ef_198002.data',
> surfQswFile='qsf_198002.data',
> /
> 
> 
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