unexpected temperature distribution ...

[turuncu]

Hi,

I try to set-up ROMS model for Caspian Sea. The result is little bit strange. The unrealistic cold regions over deepest regions. It seems that there is a problem in horizontal and vertical diffusion but i am not sure. I plot the surface and vertical temperature distribution and they can be seen at the end of the message. The used options are;

Code: Select all

/*
** Options associated with momentum equations:
*/

#define UV_ADV
#define UV_COR
#define UV_VIS2
#define UV_LDRAG
#undef  UV_VIS4

/*
** Options associated with tracers equations:
*/

#define TS_U3HADVECTION
#define TS_C4VADVECTION
#define TS_DIF2
#define SALINITY
#define SOLAR_SOURCE
#undef  TS_DIF4

/*
** Options for pressure gradient algorithm:
*/

#define DJ_GRADPS
#define ATM_PRESS

/*
** Options for atmospheric boundary layer:
*/

#define BULK_FLUXES
#define EMINUSP
#define LONGWAVE_OUT

/*
** Options for model configuration:
*/

#define SOLVE3D
#define MASKING
#undef  STATION

/*
** Options for analytical fields configuration:
*/

#define ANA_BSFLUX
#define ANA_BTFLUX
#define ANA_INITIAL

/*
** Options for horizontal mixing of momentum:
*/

#define MIX_S_UV       /* mixing along constant s surfaces */
#undef  MIX_GEO_UV     /* mixing on z surfaces */
#define MIX_GEO_TS
#undef  MIX_S_TS

/*
** Options for vertical mixing momentum and tracers:
*/

#define MY25_MIXING
#define KANTHA_CLAYSON
#define N2S2_HORAVG
#define NONLIN_EOS

/*
** Options for close boundary conditions:
*/

#define EASTERN_WALL
#define NORTHERN_WALL
#define SOUTHERN_WALL
#define WESTERN_WALL

Model has 32 vertical level and grid resolution is 10 km.

Code: Select all

  Vtransform == 2                          ! transformation equation
 Vstretching == 2                          ! stretching function
...
...     
     THETA_S == 8.0d0                      ! surface stretching parameter
     THETA_B == 0.4d0                      ! bottom  stretching parameter
      TCLINE == 10.0d0                     ! critical depth (m)

The problem might be related with the viscosity and diffusion parameters (TUN*, VISC* and AKT_BAK). What is the real effects of these parameter over the model? I have some difficulties about setting right parameters. So, is there any simple combination of them. What do you suggest?

Surface temperature (Seasonal average, MAM):
1st column AVHRR
2nd column ARCLAKE
3rd column Model Results


Bathymetry and cross section positions:


Vertical cross section of temperature field (Seasonal average, MAM):


Thanks,
Regards,

--ufuk

[susonic]

I can't see the images.

Would you attach them?

[turuncu]

Sorry about that. I don't know why you didn't see the plots but i replaced them with their gif versions. So, i can see the plots now.

--ufuk

[susonic]

Before you think about the wrong use of horizontal/vertical diffusion cpp option,
did you check out the value of surface forcing whether it's reasonable?

Sometimes we find some weird value in the forcing file due to mistake
from the building script.