how to make a forcing file with a different grid than ROMS?

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leonjld
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how to make a forcing file with a different grid than ROMS?

#1 Post by leonjld » Mon Dec 13, 2010 6:42 pm

Hi, dear roms users and developers,

I am trying to force my application directly using the atmospheric model without interpolation to the forcing fields.

on this page: http://www.myroms.org/index.php?page=forcing

it was mentioned that user can use a ascii file as forcing files, I am wondering if it is still possible with roms3.3 or the webpage is outdated?

on wikiroms:
https://www.myroms.org/wiki/index.php/F ... forcing.3F

It mentioned about "Gridded fields on a larger, usually coarser grid". But I cannot find detailed info on how to built such kind of netcdf file. The major questions are: what are the naming conventions for the coordinates (e.g., lat, lon) and what attributes are required for the variables. It will be helpful if there is a cdl template for that (coarser grid forcing). I did find cdl templates for forcing that has same grid with the model.

Thanks!

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kate
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Re: how to make a forcing file with a different grid than RO

#2 Post by kate » Mon Dec 13, 2010 8:24 pm

A cdl has been added to the wiki page you reference.

leonjld
Posts: 51
Joined: Fri Feb 27, 2004 6:30 pm
Location: NOAA/NESDIS/STAR

Re: how to make a forcing file with a different grid than RO

#3 Post by leonjld » Mon Dec 13, 2010 8:53 pm

thanks, Kate!

In the cdl on that page:

double lat(lat) ;
lat:units = "degrees_north" ;
lat:point_spacing = "uneven" ;
lat:axis = "Y" ;
double lon(lon) ;
lon:units = "degrees_east" ;
lon:modulo = 360. ;
lon:point_spacing = "even" ;
lon:axis = "X" ;


Can I define coordinate as lon(lat,lon) and lat(lat,lon) if the grid is somehow slanted? Also are the attributes such as modulo, axis, point_spacing really used by ROMS?
kate wrote:A cdl has been added to the wiki page you reference.

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kate
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Re: how to make a forcing file with a different grid than RO

#4 Post by kate » Mon Dec 13, 2010 9:10 pm

The answers are all "no". I hacked some modulo code into my branch, but did it as a CPP flag instead. Checking for "modulo" would be good. Interpolating from typical WRF grids would probably be useful too, but it's tougher.

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