Ocean Modeling Discussion

ROMS/TOMS

Search for:
It is currently Sun Sep 24, 2017 5:04 am




Post new topic Reply to topic  [ 3 posts ] 

All times are UTC

Author Message
PostPosted: Sun Mar 19, 2017 7:23 am 
Offline

Joined: Tue Mar 01, 2016 1:38 am
Posts: 36
Location: the Ocean University of China
Hello everyone,
I have a confusion about TIDE_START, I am going to develop my case followling 'create_sandy_application.m'. In ocean_sandy.in file, some time parameters setting are :

DSTART = 56228.5d0 56228.5d0 ! days
TIDE_START = 52866.0d0 ! days
TIME_REF = 18581117.0d0 ! yyyymmdd.dd

Sandy case is simulated from 27-Oct-2012 to 2-Nov-2012, So I know DSTART = Time_start(27-Oct-2012)- TIME_REF(18581117.0d0), And all the forcing files started at 56228 days. I want to know what the meaning of TIDE_START, and I usually use the TPXO2ROMS_v4pt0_script.m to create tide forcing file, if the 't0' in the script is accosiated TIDE_START ? and how to calculate the TIDE_START?


Attachments:
捕获.JPG
捕获.JPG [ 73.73 KiB | Viewed 361 times ]
Top
 Profile  
Reply with quote  
PostPosted: Sun Mar 19, 2017 8:00 pm 
Offline
User avatar

Joined: Wed Jul 02, 2003 5:29 pm
Posts: 3223
Location: IMS/UAF, USA
The idea is that TIDE_START is the tidal offset from your TIME_REF. If your tidal t0 and your DSTART match, then you have it about right (plus or minus half a day).


Top
 Profile  
Reply with quote  
PostPosted: Mon Mar 20, 2017 10:01 pm 
Offline

Joined: Mon Jun 20, 2005 3:46 pm
Posts: 87
Location: South Australian Research and Development Institute
Hi Rocky,
You have:
DSTART = 56228.5d0 56228.5d0 ! days
TIDE_START = 52866.0d0 ! days
TIME_REF = 18581117.0d0 ! yyyymmdd.dd

1. Why do you have two values of DSTART?
2. Did you mean to have DSTART=TIDE_START? Just checking, because the digits are similar but not the same.
3. You seem to have three different times (DSTART, TIDE_START, and t0 are all different, even if you add your TIME_REF to DSTART and TIDE_START).
4. t0 in TPXO2ROMS specifies time at which the tidal phase lags (aka "little g's") are computed.
5. I haven't used a TIME_REF other than -2 for years, and I usually set DSTART=TIDE_START. I set t0 the same time (but it is in Matlab datenumber).
6. Look at this section from set_tides.f90. This is where the phase is set. Run your model for one time step, printing out cff and any other variables you want to know (put a print statement in the .F file.) If t0 corresponds to the starting time step of the model, you should be right.
!-----------------------------------------------------------------------
! Add tidal elevation (m) to sea surface height climatology.
!-----------------------------------------------------------------------
!
Etide(:,:)=0.0_r8
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)
DO j=JstrR,JendR
DO i=IstrR,IendR
Etide(i,j)=Etide(i,j)+ &
& ramp*SSH_Tamp(i,j,itide)* &
& COS(omega-SSH_Tphase(i,j,itide))
Etide(i,j)=Etide(i,j)*rmask(i,j)
END DO
END DO
END IF
END DO
7. I'm surprised that Kate says "If your tidal t0 and your DSTART match..." because I thought DSTART was used only as a time stamp for stdout (i.e., not used internally for any phase calculation or anything), but then she knows way more than I ever will about ROMS. :)


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 3 posts ] 

All times are UTC


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group