Relation between hmin and resolution

[abhi_nio]

Hallo !

I want to set up a wind force circulation model for Indian ocean region. I have taken hmin= 15 meter (minimum depth to consider a grid to be an ocean grid) and resolution is 1/4 degree.

I want to know is this (hmin, resolution) consistent with ROMS or not. If not, then what should be the resolution to get hmin ~ 15 meter.

[kate]

There isn't a hard and fast rule about the relationship between hmin and resolution. However, there is a limit to how much the depth can change from one grid to the next and setting hmin to 15 m means that it will be some number of grids (more than a degree for you) between the shelf and the deep ocean. If you smooth the bathymetry to match this criterion, you will change the shape of the basin and change the resulting structure of the currents. Note that all of us who smooth the bathymetry face this dilemma.

Bernard Barnier once showed me a case where the true currents were a surface current and a deep undercurrent, stacked on top of each other, both at the shelf break. With the smoother bathymetry, the two had shifted laterally, with the undercurrent farther offshore. This changed the stability properties of the system entirely. As in all things modeling, user beware.

[abhi_nio]

Dear kate,

Thanks for your reply. Now I got some idea to resolve this problem.