Anonalous currents in shelf regions

[hpftcb]

Hi Roms forum,
I'm running a case in which my boundary conditions were built from my initial condition (initial_condition.png). It's a gausian current flowing along shelf break with 0 velocity elsewhere. The problem is I'm getting strong current velocities in the shallowest parts of my region (in the shelf area), spoiling all the simulation, as can be seen in figure last_time.png. In figure bathy.png is the cross section of the bathymetry, which is uniform along latitude

my rx0 is 1.218052E-01, and my rx1 is 7.066410E+00

I've tested different bathymetry smoothing yet I still get the same instabilities. Has anyone had the same problem? Do you think is a smoothing problem?

Thanks a lot in advance,

Fernando

[kate]

I think it's a boundary condition problem, not a bathymetry smoothing problem. Have you tried a periodic boundary condition along channel? You'd have to make the Coriolis parameter uniform for it to be truly periodic.

You haven't told us much about your setup. Is it barotropic? Is there stratification? What are your goals here? Is your surface slope in balance with the flow you want to drive?

[hpftcb]

Hi Kate, thanks for your reply

It's a baroclinic case (although I found the same problem when testing the barotropic mode). I aim to build an idealized case to study baroclinic instability problems. In this specific case the BC e IC where built from a parametrization of the Brazil Current with the TS in thermal wind balance with the velocity field. I will check the surface slope.


My BC are:

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

LBC(isTvar) == Clo RadNud RadNud RadNud ! temperature
Clo RadNud RadNud RadNud ! salinity
Clo RadNud RadNud RadNud ! dye_01

regards,

Fernando

[kate]

I would still try a periodic channel just to get things going and to make sure your initial conditions are internally consistent.