problem in setting open boundary ...

[turuncu]

Hi All,

I am trying to setup a case with open boundary only in western side of the domain. The case without open boundary the simulation works without any problem but when i open western side of the domain the model produce very high ssh around 20 m at couple of time step and crash. First, i think that it is related with boundary condition and set all the values of temperature, salinity and current to zero but the result is same and it crash in the same time step with similar reason. I also try with and without volume conservation option and different open boundary relaxation values but it did not help. Even i closed all sides (of course mask value is not land in the western side) and model crashed again in same reason. So, I just need some suggestion at this point. This is the first time that I try to use open boundary condition and my past experience about ROMS was always using closed boundaries for inland lakes and seas.

Thanks,

--ufuk

[kate]

You haven't told us exactly what you are trying for open boundary conditions. What values of LBC? If you are using any that need external values, what are you using for those? I always use OBCs that require external values and the model is sensitive to what you choose for them.

[turuncu]

Thanks Kate. Actually, my domain is Mediterranean Sea and I am trying to define OBC for Atlantic Ocean. There is a buffer zone that extends to Atlantic Ocean from Strait of Gibraltar. So, only western boundary will be open. I am not sure what do you mean external values but for OBC, i will use ORAS4 dataset from ECMWF (https://www.ecmwf.int/en/research/clima ... reanalysis). It has a monthly values for temperature, salinity, current and sea surface height. I also need to have correction for SSH in the buffer zone. I read couple of discussion about it and I think it is not good idea to have SSH correction but I would like to test it. If there is a indirect way to pose SSH correction that would be also helpful.

--ufuk

[kate]

I don't know what you mean by SSH correction in the buffer zone.

Yes, your external values are coming from a reanalysis. Monthly is likely not often enough, but should not be causing 20 m SSH.

I was also asking about Flather, Chapman, RadNud or what?

[turuncu]

I was setting OBC as follows

LBC(isFsur) == Cha Clo Clo Clo ! free-surface
LBC(isUbar) == Fla Clo Clo Clo ! 2D U-momentum
LBC(isVbar) == Fla Clo Clo Clo ! 2D V-momentum
LBC(isUvel) == Rad Clo Clo Clo ! 3D U-momentum
LBC(isVvel) == Rad Clo Clo Clo ! 3D V-momentum
LBC(isMtke) == Cha Clo Clo Clo ! mixing TKE

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

I have also SSH data from reanalysis. I just wonder that is it possible to modify ROMS calculated SSH in Atlantic buffer zone using data from reanalysis?

[fdaryabor]

Dear turuncu,
Hi

You can try "Gra" option for the turbulence kinetic energy (TKE) instead "Cha" and see how's that.

LBC(isMtke) == Cha Clo Clo Clo ! mixing TKE LBC(isMtke) == Gra Clo Clo Clo ! mixing TKE

good luck to you
Farshid