strange velocity results (need some ideas to correct them)

[qizheng]

Hi all,

I am modelling the ocean along Chilean coastline. I have run ROMS for 10 years and output the daily results. To investigate the ocean process, I generated the movies of sea surface height, temperature, salinity, meridional and zonal velocity (all at surface). Temperature, salinity and sea surface height seem likely to be reasonable, however, the meridional and zonal velocities don't make sense. My modelling result of velocity is totally different from the observation and results from other model. My results are very wrong but I am not sure how to improve them. Could anyone give me some ideas about it?

The example figures showing U(zonal velocity) and V(meridional velocity) from ROMS and observational dataset are attached. ROMS results are coloured by 'jet' (title: Sea surface U(V) at January 12,0009 12:00:00PM) and observational results are coloured by 'red blue'.

The lateral boundary conditions I used:

LBC(isFsur) == Cha Cha Cha Cha ! free-surface
LBC(isUbar) == Shc Shc Shc Shc ! 2D U-momentum
LBC(isVbar) == Shc Shc Shc Shc ! 2D V-momentum
LBC(isUvel) == Rad Rad Rad Rad ! 3D U-momentum
LBC(isVvel) == Rad Rad Rad Rad ! 3D V-momentum
LBC(isMtke) == Gra Gra Gra Gra ! mixing TKE

LBC(isTvar) == Rad Rad Rad Rad \
Rad Rad Rad Rad

The sponge layer is customised by giving my own viscosity coefficients in grid.nc.

Other details showed in roms.in and cppdef.h files are also attached.

Any idea/hint will be very helpful!


Best Regards
Qi

[jcwarner]

not sure it is a BC issue.
what are you using for TS advection? turb closures?
do you N2S2_HORAVG on??
-j

[qizheng]

Dear Jcwarner,

Thank you for your reply.


The TS-related options are:
# undef TS_DIF2
# undef TS_DIF4
# define MIX_ISO_TS
Hadvection == SU3 \ ! temperature
SU3 ! salinity
Vadvection == A4 \ ! temperature
A4 ! salinity

The vertical turbulent mixing scheme I used is LMD_MIXING so I did not turn on the N2S2_GORAVG

Best Regards
Qi

[jcwarner]

do the temp and salt fields looks blocky?

[xavierC]

did you try
#define TS_DIF4

# define MIX_GEO_TS/UV
#define TS_DIF4/UV
I know this should be not activated with SU3 but from my little experience with this branch of ROMS it helps solving this kind of trouble.
You may also try TKE or GLS

[qizheng]

Dear xavierC，

Thank you for your reply. I will have a try based on your suggestions!


Best Regards
Qi