[MITgcm-devel] seaice dynamics in ocean 2-D

[Jean-Michel Campin]

Hi Martin,

I am trying to reproduce results from ~1.5 year ago (close to checkpoint65j), 
with a 2-D (y-z) southern ocean channel, and am am getting very different seaice 
velocity.
I am using pkg/thsice thermodyn with pkg/seaice dynamics, deltaT=1.h
and my data.seaice is attached.

I can reproduce the old results when I use:
 - full code from checkpoint65j (Feb 25, 2015) 
 - or just pkg/seaice from checkpoint65j into latest code

I made a short (10.iter) comparison between c65j (d12a) and latest code (d12c),
starting from a pickup of the old run. The largest difference are on vIce as 
seem on this plot (x-axis = latitude, magenta and red are d12a results
at iter 1 and 9 respectively; green, yellow, ceilan and blue are d12c results
at iter 1 3 5 and 9).

Do you have any suggestion of what could cause these large difference ?

Cheers,
Jean-Michel
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# SEAICE parameters
 &SEAICE_PARM01
#SEAICErestoreUnderIce=.TRUE.,
 usePW79thermodynamics=.FALSE.,
 SEAICE_strength    = 2.6780e+04,
 OCEAN_drag         = 8.1541e-04,
 SEAICE_waterDrag   = 5.3508,
#SEAICE_waterTurnAngle= 25.,
#LSR_ERROR       = 1.E-12,
#LSR_ERROR       = 2.E-9,
 SEAICElinearIterMax=500,
#SOLV_MAX_ITERS  = 500,
 SEAICE_OLx = 1,
 SEAICE_OLy = 1,
 SEAICE_EPS = 2.e-9,
#SEAICEuseStrImpCpl=.TRUE.,
#LSR_mixIniGuess = 2,
#SEAICEuseMultiTileSolver=.TRUE.,
#NPSEUDOTIMESTEPS = 10,
#---
#  SEAICEuseJFNK       = .TRUE.,
#  SOLV_MAX_ITERS      = 10,
#  SEAICEnewtonIterMax = 200,
#  SEAICEkrylovIterMax = 50,
#  JFNKgamma_nonlin    = 1. _d -05    # default
#  JFNKgamma_lin_min   = 0.10 _d 0   # default
#  JFNKgamma_lin_max   = 0.99 _d 0   # default
#  JFNKres_tFac        = 0.5
#  SEAICE_JFNKepsilon  = 1. _d -06 # default
#  SEAICE_JFNKalpha    = 1.5, # a bit more agressive than the default
#---
 SEAICE_no_Slip     = .FALSE.,
#SEAICEwriteState   = .TRUE.,
#SEAICE_clipVelocities = .TRUE.,
 SEAICE_monFreq = 2592000.,
 SEAICE_monFreq = 1.,
 &

 &SEAICE_PARM03
 &
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