nested domain blow up

[fanqing]

I am running ROMS with a small nested domain embedded in a larger parent domain.

on the east boundary of the nested domain, some perturbation grows gradually and eventually become too big, and the model blows up.

The perturbation is fed back into the parent domain. So the problem can be see on both.

When I run the small domain only, it can run fine.

The attached picture shows the bottom level current, U, on both parent and nested domain, right before the model blow up.

Any ideas how to solve this problem? Seems to be due to some kind of mis-match between the nest and parent.

Any suggestions are appreciated.