[MITgcm-support] SOM instability after checkpoint 64e

[Spencer Jones]

Hi everyone,
I'm trying to update my code tree before I start a new project, but I'm
finding that SOM is unstable in my setup from checkpoint 64e onwards. With
the flux limiter off (advection scheme 80), the temperature becomes large
and negative. With the flux limiter on (advection scheme 81), the
temperature remains positive, but I get an unphysical-looking standing wave
in the zonal direction at mid-latitudes.

I have tried changing the viscosity, diffusivity and various other things
but to no avail. Does anyone know what's going on? My data file is pasted
below.
Thanks very much,
Spencer

# ====================

# | Model parameters |

# ====================

#

# Continuous equation parameters

 &PARM01

 tRef = 32*0.,

 sRef = 32*35.,

 no_slip_bottom=.TRUE.,

 no_slip_sides=.TRUE.,

 viscAr=1.E-4,

 viscAh=40.E3,

# diffKrT=1.E-5,

 diffKrNrT=0.0083, 0.0065, 0.0038,0.0014, 0.00039,0.000092,

           0.00003, 0.00002,0.00002,0.00002,0.00002,0.00002,

           0.00002,0.00002,0.00002,0.00002,0.00002,0.00002,0.00002,0.00002,

           0.00002,0.00002,0.00002,0.00002,0.00002,0.00002,0.00002,0.00002,

           0.00002,0.00002,0.00002,0.00002,

# diffKrS=2.E-5,

 diffKrNrS=0.0083, 0.0065, 0.0038,0.0014, 0.00039,0.000092,

           0.00003, 0.00002,0.00002,0.00002,0.00002,0.00002,

           0.00002,0.00002,0.00002,0.00002,0.00002,0.00002,0.00002,0.00002,

           0.00002,0.00002,0.00002,0.00002,0.00002,0.00002,0.00002,0.00002,

           0.00002,0.00002,0.00002,0.00002,

 rhonil=1035.,

 rhoConstFresh=1000.,

 eosType = 'LINEAR',

 ivdc_kappa=10.,

 implicitDiffusion=.TRUE.,

 bottomDragLinear=1.E-3,

 exactConserv=.TRUE.,

 useRealFreshWaterFlux=.FALSE.,

 useSingleCpuIO=.TRUE.,

# turn on looped cells

 hFacMin=.1,

 hFacMindr=50.,

# set precision of data files

 readBinaryPrec=32,

 tempAdvScheme=81,

 saltAdvScheme=81,

 staggerTimeStep=.TRUE.,

 debugLevel=-1,

 &


# Elliptic solver parameters

 &PARM02

 cg2dMaxIters=500,

 cg2dTargetResidual=1.E-13,

 printResidualFreq=37606140,

 &

# Time stepping parameters

 &PARM03

 nIter0=13000000,

 nTimeSteps = 4800000,

# 100 years of integration will yield a reasonable flow field

# startTime =          0.,

# endTime   = 3110400000.,

 deltaTmom = 900.,

 deltaTtracer= 10800.,

 deltaTClock = 10800.,

 deltaTfreesurf= 5400.,

 abEps = 0.1,

 pChkptFreq= 4320000000.,

 chkptFreq=  4320000000.,

 dumpFreq= 43200000000000.,

 monitorFreq=86400000.,

# 10 days restoring timescale for temperature

 tauThetaClimRelax=  864000.,

# 6 months restoring timescale for salinity

# tauSaltClimRelax = 15552000.,

# periodicExternalForcing=.FALSE.,

# externForcingPeriod=2592000.,

# externForcingCycle=31104000.,

 pickupStrictlyMatch=.FALSE.,

 &


# Gridding parameters

 &PARM04

 usingSphericalPolarGrid=.TRUE.,

 delR= 32*125.,

 ygOrigin=-70.,

 dySpacing=0.9722,

 dxSpacing=0.9722,

 &


# Input datasets

 &PARM05

 bathyFile=      'bathy.bin',

 zonalWindFile=  'taux.bin',

 meridWindFile=  'tauy.bin',

 thetaClimFile=  'sst2.bin',

# saltClimFile=   'lev_sss.bin',

# surfQFile=      'ncep_qnet.bin',

# the_run_name=   'global_oce_latlon',

# fresh water flux is turned on, comment next line to it turn off

# (maybe better with surface salinity restoring)

 EmPmRFile=      'sflux.bin',

 &
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