Dstart, and tide_start

[azhang]

Hi, John,
Thanks a lot for your quick anwsers for my question. In my application,
I set DSTART and TIDE_START as you said as,

DSTART=151.0 for Days of Jun1 1, 1990 from Jan. 1, 1990
TIDE_START=0.0

I assumed the model simuated beginning from June 1, 1990 in this way.
However, The model simulation time in the ROMS output files (ocean_time in history and station files) still started from 0, not started from 151*86400.0 as assumed. Do you have any clue about this? Should I set TIDE_START=151 as well.

Thanks

[jcwarner]

set_tides.F has:

cff=2.0_r8*pi*(time(ng)-tide_start*day2sec)
DO itide=1,NTC
IF (Tperiod(itide).gt.0.0_r8) THEN
omega=cff/Tperiod(itide)
.......


so .....
if your tides are referenced to jan 1 1990, then i think you should use tide_start = 0.

[longmtm]

For me, I have

DSTART = 6940.0d0 ! days after TIME_REF, i.e. 1999 01 01
TIDE_START =0.0 ! days after tide forcing time axis origin
TIME_REF = 19800101.0d0 ! yyyymmdd.dd

TIDE_START totally depends on how you prepare the tidal forcing, i.e. how you generate the nodal factors and equilibrium arguments, You will need to
input starting time, and length of time of your tidal forcing to do that. If your input starting time is TIME_REF+DSTART, then you should have TIDE_START=DSTART

IF your input starting time is TIME_REF, then your should have TIDE_START=0 ,

i.e. TIDE_START is the offset of starting time (you used to generate nodal factors and equilibrium arguments) from TIME_REF in days.

Wen