[MITgcm-support] Troubleshooting Gridding for Near N-Pole Simulation

[Benjamin Ocampo]

Hi All:

I am a little confused about using MITgcm to model fluid behaviour near the
pole,

When I set the following variables in the data file:

ygOrigin = 66.0
delY = 50.0*0.5

The program does not crash (i.e. the temperature average does not diverge
to NaN with increasing time). However, when I set the variables to:

ygOrigin = 65.0
delY = 50.0*0.5

or

ygOrigin = 64.0
delY = 50.0*0.5

the temperature average of the fluid diverges to NaN (typically to +
infinity at roughly 40 time steps). I am wondering if anyone knows why this
is the case.

This is the current data file for the case that did work:

# Model parameters
# Continuous equation parameters
 &PARM01
 tRef=40*25.,
 sRef=40*25.,
 viscAz=7.5E-2,
 viscAh=7.5E-2,
 no_slip_sides=.FALSE.,
 no_slip_bottom=.FALSE.,
 diffKhT=7.5E-2,
 diffKzT=7.5E-2,
 rotationPeriod=6283185,
 beta=0.0,
 tAlpha=1.3106E-12,
 sBeta =0.,
 gravity=9.81,
 rhoConst=1000.0,
 rhoNil=1000.0,
 saltStepping=.FALSE.,
 saltAdvection=.FALSE.,
 saltForcing=.FALSE.,
 rigidLid=.FALSE.,
 implicitFreeSurface=.TRUE.,
 nonHydrostatic=.TRUE.,
 eosType='LINEAR',
 readBinaryPrec=64,
 useSingleCpuIO=.TRUE.,
 debugLevel=-1,
 debugMode=.FALSE.,
 &
# Elliptic solver parameters
 &PARM02
 cg2dMaxIters=1000,
 cg2dTargetResidual=1.E-13,
 &
# Time stepping parameters
 &PARM03
 startTime=0.0,
 endTime=30000000.0,
# startTime=30000000.0,
# endTime=120000000.0,
 deltaT=750.0,
# deltaTmom=1200.0,
# deltaTtracer=1200.0,
 abEps=0.1,
 pChkptFreq=30000000.0,
 chkptFreq=0.0,
 dumpFreq=300000.0,
 monitorFreq=30000000.,
 &
# Gridding parameters
 &PARM04
 usingSphericalPolarGrid=.TRUE.,
 delZ = 14.6712, 29.2561, 43.6692, 57.8262, 71.6437,
        85.0408, 97.9389, 110.262, 121.939, 132.899,
        143.080, 152.421, 160.868, 168.370, 174.885,
        180.373, 184.803, 188.148, 190.389, 191.513,
        191.513, 190.389, 188.148, 184.803, 180.373,
        174.885, 168.370, 160.868, 152.421, 143.080,
        132.899, 121.939, 110.262, 97.9389, 85.0408,
        71.6437, 57.8262, 43.6692, 29.2561, 14.6712,
 ygOrigin=66.0,
 rSphere=6.37E+6,
 delX=360*0.5,
 delY=50*0.5,
 &
 &PARM05
# bathyFile='topog.box',
 hydrogThetaFile='ThetaR0.bin',
 uVelInitFile =  'uvelinit.bin',
 vVelInitFile =  'vvelinit.bin',

Cheers,
Benjamin
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