[MITgcm-support] orlanski and prescribe bc's

[Sutherland David]

Hi all,

I am working on setting up a high-resolution, regional application of the MITgcm, where the forcing is imposed at the boundaries (from a larger domain ROMS model). Tides are important, as are the BC's for T and S, and we are interested in using the MITgcm b/c of its nonhydrostatic and finite volume codes. I have got the model to run using OBCSprescribe, but have to use the OBCSbalance routine to ensure that eta doesn't drop 10's of meters over the run. 

I am wondering about a different approach of prescribing velocities (and hence the tides) on 1 incoming boundary and letting them radiate away at the other boundary. But, I'd also like to keep prescribing T and S at all boundaries. My understanding is if you turn on OBCSprescribe, this supersedes all other BC's- so I need to modify some of the obcs code to allow some boundaries to be prescribed (1 u/v, all T/S) and others to radiate (1 u/v)? 

Has this been done before? Any suggestions or corrections to my understanding? I want to radiate things away because although the model runs right now, and a nice estuarine salinity gradient sets up, the SSH fields are not right, as barotropic waves just slosh around the domain. 

Thanks,

Dave Sutherland