[MITgcm-support] NaNs in output

[Fengchao Yao]

I am using curvilinear coordinates read from a file and the horizontal resolution is about 1.8 km. The time step is 300s. The model is forced with constant forcing with relaxation to boundary conditions.

Fengchao
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Fengchao Yao (姚凤朝), Ph.D.
RM 4405 Building No. 1
Mathematical and Computer Science and Engineering Division
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________________________________________
From: Martin Losch [Martin.Losch at awi.de]
Sent: Monday, October 01, 2012 9:39 AM
To: mitgcm-support at mitgcm.org
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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