need help interpreting erroneous ROMS results

[youngstor]

Hi ROMS forum,

I am running a ROMS simulation with prescribed BC and initial condition from an existing model solution. However when I look at the time evolution of the velocities at the northern boundary and also an arbitrary cross-section in the middle of the domain, I see this really strange irregularity develop from surface all the way to the bottom. But such irregularity doesn't exist in the parent grid that I extract the BC and initial condition from.

I am looking for guidance or whatever thoughts coming to your mind when you first see the problem. I tried different things, and ran out of ideas ...

Thanks

Here is a quick preview of the problem:

Northern boundary - u :

u velocity at north boundary

Northern boundary -v :

v velocity at northern boundary

middle of the domain - u:

u velocity of a cross-section in the middle of the domain

middle of the domain - v:

v velocity of a cross-section in the middle of the domain

Following are the evolution animation:
https://drive.google.com/file/d/0B4lTWc ... sp=sharing
northern boundary - v:
https://drive.google.com/file/d/0B4lTWc ... sp=sharing

middle of the domain - u:
https://drive.google.com/file/d/0B4lTWc ... sp=sharing
middle of the domain - v:
https://drive.google.com/file/d/0B4lTWc ... sp=sharing

[rsoutelino]

What type of open boundary conditions are you using? With which variables and with which frequency are you feeding your boundaries? Using Volcons? Could you post your ocean.in and a log file from the simulation so we can have a better idea of your configs?

[youngstor]

I am using daily boundaries interpolated from existing model solutions obtained from our colleagues. I know daily BC might not be good enough, but that's all we have so far. We are trying to find higher freq. results. I didn't use VolCons.

I think you have pointed me to the right direction. I had a look at the velocities on the boundaries of the donor grid and my grid, and I noticed some mismatch in bathymetry (such bathymetry mismatch can also be seen in the figures of the post). I am suspecting the bathymetry difference has caused the issue. I am working on it, and hopefully can find a fix soon!

Thank you for responding!

What type of open boundary conditions are you using? With which variables and with which frequency are you feeding your boundaries? Using Volcons? Could you post your ocean.in and a log file from the simulation so we can have a better idea of your configs?