Ocean Modeling Discussion

ROMS/TOMS

Search for:
It is currently Sun Jul 21, 2019 7:18 am




Post new topic Reply to topic  [ 5 posts ] 

All times are UTC

Author Message
 Post subject: Tide Phase Problem
PostPosted: Mon May 13, 2019 5:18 pm 
Offline

Joined: Wed Oct 22, 2003 6:59 pm
Posts: 34
Location: U. Wash., USA
I have a realistic run that uses tidal forcing from TPXO7.2 at the boundaries, both SSH and UV. The tidal forcing runs perfectly in general. I make some hand adjustments the the tidal amplitude when I make the forcing, to better match observations. This also works fine. However when I try to make adjustments to the phase, adding or subtracting a constant number of degrees to tide_Ephase and tide_Cphase, the model blows up, regardless of time step. Detailed symptoms: it will run if I just add 1 degree, but not if I add (or subtract) 10 degrees or more. It also blows up if I only adjust tide_Ephase and not tide_Cphase. The confusing thing to me is that all I am doing is changing the timing of high tide, not the amplitude.

Thanks for your help!

Parker


Top
 Profile  
Reply with quote  
 Post subject: Re: Tide Phase Problem
PostPosted: Mon May 13, 2019 6:21 pm 
Offline

Joined: Wed Dec 31, 2003 6:16 pm
Posts: 786
Location: USGS, USA
basic Q: but are you adding the phase in radians? Ephase would have the most impact. are you adding to all the freqs or just some?


Top
 Profile  
Reply with quote  
 Post subject: Re: Tide Phase Problem
PostPosted: Mon May 13, 2019 6:31 pm 
Offline

Joined: Wed Oct 22, 2003 6:59 pm
Posts: 34
Location: U. Wash., USA
I am adding to all 8 tidal frequencies, and doing so in degrees in my "tides.nc" forcing file. My varinfo.dat implies to me that the input should be in degrees and that ROMS (rev. 823) converts it internally to radians:

'tide_Ephase' ! Input
'tidal elevation phase angle'
'degrees' ! [radians]
'SSH_Tphase, scalar, series'
'tide_period'
'idTzph'
'r2dvar'
0.017453292519943295 ! pi/180


Top
 Profile  
Reply with quote  
 Post subject: Re: Tide Phase Problem
PostPosted: Mon May 13, 2019 6:42 pm 
Offline

Joined: Wed Dec 31, 2003 6:16 pm
Posts: 786
Location: USGS, USA
ok. i forgot how the input went. mine does the same: tide_Ephase in degress in netcdf, varinfo converts to rads.
Do you use ramp_tides? What if you adjust tide_start in the ocean.in.
-j


Top
 Profile  
Reply with quote  
 Post subject: Re: Tide Phase Problem
PostPosted: Mon May 13, 2019 7:22 pm 
Offline

Joined: Wed Oct 22, 2003 6:59 pm
Posts: 34
Location: U. Wash., USA
Thanks for the suggestions. I stopped using ramp_tides because (1) it seemed to handle the "rude awakening" without blowing up, and (2) it meant that I always had to make 2 versions of the executable. If I were always doing long "cold start" runs I could just have the ramp_tides version, but my forecast model workflow means I need to start most of the time without ramp_tides.

Note: my vote for future development would be to move the ramp_tides decision to the .in and out of the .h.

I'll try fiddling with tide_start. Ideally I wanted to adjust the phases individually to best match observations.

PM


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 5 posts ] 

All times are UTC


Who is online

Users browsing this forum: No registered users and 2 guests


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:  
cron
Powered by phpBB® Forum Software © phpBB Group