[MITgcm-support] Salinity variability malfunction

[Иван Запорожцев]

Dear MITgcm expert!

I am a novice user of MITgcm and I would be grateful to get a piece of
advice from you.
The task is regional modelling for real water area. Time steps for
calculation are 100 s. Space step is 0.1 degree for both lon/lat. Area has
approximately 50 by 20 degrees grid. Depth levels are 0.5 m wide (16 layers
in depth => depth is 10 m as average). Forcing files are from JRA25.
Initial temperature and salinity are set as constants (20 deg C and 11
psu). After approximately 48000 iterations (step is 100 sec) salinity
changes by only 0.5 psu (from 11 psu). I have values: diffKhS=0.,
 diffKrS=3.E-5. Then I carried out experiments changing coeffs above from
1.0E-5 to 1.0E5 and have no reasonable differences.

Is this situation normal (it requires much more time to change constant
salinity significantly)?
Or maybe I mistakenly switched off effective usage of these coeffs?

I use the following in main data file

no_slip_sides=.FALSE.,
 no_slip_bottom=.TRUE.,
 viscAr=1.E-3,
 viscAh=1.E2,
 diffKhT=0.,
 diffKrT=3.E-5,
 diffKhS=0.,
 diffKrS=3.E-5,
 rigidLid=.FALSE.,
 implicitFreeSurface=.TRUE.,
 eosType='JMD95Z',
 saltStepping=.TRUE.,
 tempStepping=.TRUE.,
 momStepping=.TRUE.,
 implicitDiffusion=.TRUE.,
 implicitViscosity=.TRUE.,
 allowFreezing=.TRUE.,
 exactConserv=.TRUE.,
 useCDscheme=.TRUE.,

And the following in CPP Options

#define SHORTWAVE_HEATING
#define INCLUDE_PHIHYD_CALCULATION_CODE
#define INCLUDE_CONVECT_CALL
#define INCLUDE_CALC_DIFFUSIVITY_CALL
#undef ALLOW_BL79_LAT_VARY
#undef ALLOW_3D_DIFFKR
#define INCLUDE_IMPLVERTADV_CODE
#undef ALLOW_ADAMSBASHFORTH_3
#define ALLOW_SRCG
#undef ALLOW_NONHYDROSTATIC
#define ATMOSPHERIC_LOADING
#undef EXCLUDE_FFIELDS_LOAD
#define EXACT_CONSERV
#undef NONLIN_FRSURF
C#define COSINEMETH_III
#undef  OLD_ADV_BCS
#undef OLD_GRID_IO
#include "CPP_EEOPTIONS.h"
C o Include/exclude code specific to the ECCO/SEALION version.
C   AUTODIFF or EXF package.
C   Currently controled by a single header file
C   For this to work, PACKAGES_CONFIG.h needs to be included!
cph#if (defined (ALLOW_AUTODIFF) || \
cph     defined (ALLOW_ECCO) || \
cph     defined (ALLOW_EXF))
cph# include "ECCO_CPPOPTIONS.h"
cph#endif
#endif /* CPP_OPTIONS_H */

I look forward to hearing from you.

Yours sincerely,
Zaporozhtsev Ivan,
Postdoctoral Research Fellow
Murmansk State Arctic University
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