[MITgcm-support] sea ice volume conservation

[Georgy Manucharayan]

Hi all,

I am running MITGCM with the sea ice package in a configuration that has 
thermodynamics turned off (i.e. using #define DISABLE_SEAICE_GROWTH in 
CPP_OPTIONS.h). The domain is closed. While the sea  ice is being 
advected by the ocean currents only, its total volume (diagnosed as 
HEFF*AREA) is not conserved. In fact, the volume is quickly decreasing 
(by ~20% within the first few days). This is problematic for my analysis.

I have confirmed through diagnostics that the thickness changes due to 
ice-ocean and atm-ice fluxes are indeed absent (i.e. 
'SIatmQnt','SIatmFW','SIfwSubl','SIdHbOCN','SIdHbATC' are all zeros). 
Surface temperature of the ocean also does not change, implying that the 
ice is not melting. Are there any other possible fluxes that might lead 
to ice loss when thermodynamics is off?

Can the ice volume loss be related to the numerical advection schemes 
that do not conserve volume when independently advecting area and 
thickness? I have tested SEAICEadvScheme = 77 and 7 which give nearly 
identical results, while scheme 2 is unstable (too much ice growth). 
Below are some of the relevant parameters from my data.seaice file.

  &SEAICE_PARM01
   SEAICE_no_slip     = .TRUE.,
   SEAICE_drag        = 0.001,
   SEAICE_tempFrz0    = -1.96,
   SEAICE_dTempFrz_dS =0,
   SEAICE_multDim     = 1,
   SEAICE_mcPheeTaper = 0.92,
#- seaice I/O params:
   SEAICEwriteState   = .TRUE.,

  &SEAICE_PARM03
   SItrNumInUse       = 2,
   SItrName(1)        = 'age',
   SItrMate(1)        = 'AREA',
   SItrUnit(1)        = 's',
   SItrName(2)        = 'one',


Any suggestions are highly appreciated,
Georgy

-- 
Georgy Manucharyan,
Stanback Postdoctoral Scholar,
Environmental Science and Engineering,
California Institute of Technology,
MS 131-24, 1200 California Blvd,
Pasadena, CA, 91125

Office: L+R, Room 226; Tel: (626) 395-8715
Web: http://www.its.caltech.edu/~gmanuch