nesting grids

[nils.lindeen]

hi,

i am working on nesting a 70 x 40 km grid inside a 450 x 350 km grid. it is the first time i am nesting grids, so have absolutely no idea how to proceed. i am having problems with creating my input tide file for my small grid, from my output tide information of my large grid. can someone please help me or give me some pointers on how to create my input tide file from my output tide information of the large grid?

i have spent a few days trying to solve this problem but have been unable, i hope there is some kind of routine that can help me do this automatically. all the routines i have found up until know have not been very well explained. for my large original grid, i used the otps2frc routine to create my input file, yet know i cannot manage to figure out the way to create my input for the small grid.

thank you!

regards,

nils

[kate]

What version of ROMS is this? The trunk code? Can you wait for ROMS 4 with the built-in nesting? If it's AGRIF, I can't answer anything.

For ROMS-to-ROMS interpolation in off-line nesting, we use scrip from a Python script. The trouble with tides are that the timescales are so short, you probably want to communicate at least hourly. Or are you computing tidal constituents from the big grid for the small grid? We need more details.

[nils.lindeen]

Thanks for your reply Kate. I am using the latest ROMS version 3.4, not AGRIF. Although I've heard AGRIF has various friendly routines.

I have been trying with ROMS_Interpolation routines, yet it's use is not that simple and not so well explained. What I am doing is grabbing my output tide time series and trying to interpolate it onto my small grid, in order to use that information as input to my small grid. I am thinking of an offline nesting, unless you recommend an online nest. Do you know of any simple routines that can help me do this?

Thanks once again.

Regards,

Nils

[susonic]

Are there any specific reasons why you want to use tide information from
large domain result?

-JH

[kate]

If I really wanted to capture the tides from the large domain to use as boundary conditions for the small domain, I would use stations where the inner nest boundary points are then convert them to a boundary file for the small domain.

What we've actually done is filter the tides and save daily, then use Python to create a boundary file, then add tides from OTPS to both domains.