freq. of communication between parent and child?

[youngstor]

Hi ROMS forum,

I was looking for the information about how frequent the parent grid and child grid communicate and exchange information in nested ROMS, but couldn't find it in the ocean.in ... I couldn't find it at wikiROMS either ...

Where can I find such information? Is it something users can change?

Thanks,
Xiufeng

[jcwarner]

in COAWST (and soon in Rutgers version) you just set the time step of the child and the parent in the ocean.in. You need to make sure that the child time steps equally into the parent step. so for example:
parent step 60 sec, child 20 sec = ok
parent step 60 sec, child 10 sec = ok
parent step 60 sec, child 24 sec = not ok

you do not need to use the grid refinement ratio to specify the time step ratio, but it would be a good palce to start.
-j

[youngstor]

Thanks John!

in COAWST (and soon in Rutgers version) you just set the time step of the child and the parent in the ocean.in. You need to make sure that the child time steps equally into the parent step. so for example:
parent step 60 sec, child 20 sec = ok
parent step 60 sec, child 10 sec = ok
parent step 60 sec, child 24 sec = not ok

you do not need to use the grid refinement ratio to specify the time step ratio, but it would be a good palce to start.
-j