here i wanna to make a simple test case in which model is only forced by tidal.i have some basic questions about tidal forcing. i have read some posts about this,but i am still not sure about these.

**1**.if the tidal forcing could be given in the boundary files? for example,my cases only has one south open boundary,can i impose the tidal forcing just by prescribing elevations and currents at south boundary without providing the tidal forcing file containing some harmonic constants of elevation and current.if only boundary files is possible,then i do not need the tidal forcing file,if not,why?

**2**.some posts said that both tidal elevations and currents on the open boundary should been given for tidal forcing case,i don not sure if this is true.if so ,why not simply providing the tidal elevations with normal currents at the open boundary set to zero.

**3**why the tidal forcing should be given at the whole grid?it is seems that ROMS only uses the ones along open boundary.

i am new to roms and ocean model so above questions perhaps are quite basic.and i am looking forward to some reply or explain about this.

any reply will be appreciable!

thanks!