why warm ssts in summer months ?

[mashinde]

Dear Roms Users,

I am forcing the MODEL with 6hourly era intrim data for test run for 1998. I use following variables....

ROMS_uwind --> ERA_Intrim_u10 (10 metre U wind component)
ROMS_vwind --> ERA_Intrim_v10 (10 metre V wind component)
ROMS_tair --> ERA_Intrim_t2m (2 metre temperature)
ROMS_pair --> ERA_Intrim_msl (Mean sea level pressure)
ROMS_qair --> ERA_Intrim_q (Specific humidity at 1000 level)
ROMS_rainfall --> ERA_Intrim_tp (Total precipitation)
ROMS_lwrad_down --> ERA_Intrim_strd (Surface thermal radiation downwards)
ROMS_swrad --> ERA_Intrim_ssr (Surface solar radiation)

the units are : tair(K), uwind & vwind(m/s), pair(mb), qair(g/kg) AND
rainfall is converted from meter to kg/m^2/s as tp * 1000.0/(3600.0*6) ,
lwrad_down is converted from W m**-2 s to W m**-2 as strd*(1/3600*6),
swrad is converted from W m**-2 s to W m**-2 as ssr*(1/3600*6)

with this units and conversion, i ran model for one year(1998,test run), then it gives warm ssts in summer months, montlhy figure attached here.
my cppdefs.h is as follows :


/* Basic physics options */
#define UV_ADV
#define UV_COR
#define UV_VIS4
#define MIX_S_UV
#define TS_DIF4
#define MIX_GEO_TS
#define SOLVE3D
#define SALINITY
#define NONLIN_EOS

/* Basic numerics options */
#define TS_U3HADVECTION
#define TS_C4VADVECTION

#define DJ_GRADPS
#define SPLINES
#define CURVGRID
#define MASKING

/* Outputs */
#define AVERAGES
#define DIAGNOSTICS_UV

#define UV_QDRAG
#define VISC_GRID
#define DIFF_GRID

#define BULK_FLUXES
#ifdef BULK_FLUXES
#define EMINUSP
#define LONGWAVE_OUT
#endif

#define SOLAR_SOURCE
#define DIURNAL_SRFLUX

#undef SRELAXATION

/* Analytical options */
#define ANA_BSFLUX
#define ANA_BTFLUX

#define GLS_MIXING
#if defined GLS_MIXING || defined MY25_MIXING
#define KANTHA_CLAYSON
#define N2S2_HORAVG
#define CANUTO_A
#define CRAIG_BANNER
#define CHARNOK
#endif

/* Open boundary condition settings */
#define EASTERN_WALL /* for close the boundary option */

#define SOUTH_FSCHAPMAN /* free surface Chapman condition for south boundary */
#define NORTH_FSCHAPMAN /* free surface Chapman condition for north boundary */
#define WEST_FSCHAPMAN /* free surface Chapman condition for west boundary */
#define SOUTH_M2FLATHER /* 2D momentum Flather condition for south boundary */
#define NORTH_M2FLATHER /* 2D momentum Flather condition for north boundary */
#define WEST_M2FLATHER /* 2D momentum Flather condition for west boundary */
#define SOUTH_TRADIATION /* tracer radiation condition for south */
#define SOUTH_TNUDGING /* tracers passive/active nuding term for south */
#define NORTH_TRADIATION /* tracer radiation condition for north */
#define NORTH_TNUDGING /* tracers passive/active nuding term for north */
#define WEST_TRADIATION /* tracer radiation condition for west */
#define WEST_TNUDGING /* tracers passive/active nuding term for west */
#define ANA_FSOBC
#define ANA_M2OBC
#define TCLIMATOLOGY /* processing tracers climatology */
#define TCLM_NUDGING /* nudging tracers climatology */

#include "globaldefs.h"

/* END */


so, can anybody tell why i am getting warm ssts in summer months. Does radiations fields I am using are correct? is anything missing/wrong in cppdefs.h ?
any suggestions/hints/comments to fix it?

thanks

[kate]

The DIURNAL_SRFLUX option is to apply a day-night cycle to daily inputs. Is your shortwave radiation daily or six-hourly? I don't know what the DIURNAL_SRFLUX would do to six-hourly inputs. Perhaps try turning it off.

Also, you don't have ALBEDO defined. I know it needs clouds - do you have clouds? Does Era have albedo as a field? Perhaps use that instead. Some albedo - any albedo - will send some of the incoming radiation back out.

[mashinde]

Hi kate,

(1) All forcings are 6 hourly. The short wave radiation is Net surface short wave radiation, I think it included cloud effect. Yes, there is albedo field in ERA.
let me try without diurnal_srflux.

(2) which short wave radiation field is required : Surface Net Short Wave Radiation OR Downward Short Wave Radiation? Currently, I am using Surface Net Short Wave Radiation.


Thanks

[kate]

In my experience, the model is very sensitive to incoming radiation, including what you do about albedo. Try things and go with what gives you the most credible answer.

[ymamoutos]

Greetings mashinde,

I would like to ask you if you are using any point sources (forcing file) for the inflow into the Mediterranean from the Dardanelles straits, Gibraltar and Nile river. If not why? These sources are critical for the circulation and T-S in the Mediterranean.

Giannis