How to handle land boundaries

Discussion of how to use ROMS on different regional and basin scale applications.

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lcbernardo
Posts: 71
Joined: Wed Oct 01, 2014 8:57 pm
Location: Tokyo Institute of Technology

How to handle land boundaries

#1 Post by lcbernardo » Tue Jan 06, 2015 5:30 am

Hi everyone,

I have a simple question regarding land boundaries/land masking in the ROMS model. I have been modifying some of the ROMS matlab scripts for creating initial and boundary conditions for my study site, and I notice that in the temperature and salinity fields, the value 65535 is inserted in the grid cells masked out as land. I tried to use the input files I created and immediately the run blows up. In the output however, I notice lines such as:

(Tmin= 0.0000 Tmax= 10.0000)
(Min = 3.39651375E+01 Max = 6.55350000E+04)

in the boundary information. Does ROMS automatically recognize 65535 as a cell masked out as land? Or is it better to set such values to maybe zero, or a realistic value?

Best regards,
Lawrence

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kate
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Joined: Wed Jul 02, 2003 5:29 pm
Location: IMS/UAF, USA

Re: How to handle land boundaries

#2 Post by kate » Tue Jan 06, 2015 6:30 pm

ROMS will check for a _FillValue attributes on fields it reads in. If the matlab scripts set this on the fields it writes you should be OK. Also, if there are wonky values inside the land mask, I would have thought ROMS wouldn't care, since it zeroes them out at run time.

If you make a grid, make the ini/bc files, then edit the land mask, that could be trouble.

lcbernardo
Posts: 71
Joined: Wed Oct 01, 2014 8:57 pm
Location: Tokyo Institute of Technology

Re: How to handle land boundaries

#3 Post by lcbernardo » Wed Jan 07, 2015 3:29 am

Hi Kate,

Thank you for your reply and advice. I'll look more closely into the _FillValue attribute. I'll also try getting rid of the wonky values and see what happens with the model run.

Lawrence

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