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Re: [ferret_users] reading ascii data ?

Hi Chamarthi,
How are the longitudes and latitudes arranged in your input file? One method as others have suggested is to interpolate the data onto a regular grid, but if we can work out how to read the longitude and latitude locations into a 2-dimensional grid, and the data field onto the correct 3-dimensional grid, then you could visualize the data on the curvilinear grid without regridding it.

For plotting data on the curvilinear grid, Ferret expects that the longitudes and latitudes, as well as the data field are arranged on a grid in X and Y where X and Y are just index values 1 to M and 1 to N, so that after opening the file and defining the grid correctly, you could do a SHOW DATA command, and see something like this:
yes? show data
    1> /home/porter/ansley/data.dat  (default)
 name     title          I         J         K         L
 LON     Longitude      1:180     1:173     ...       ...
 LAT     Latitude       1:180     1:173     ...       ...
 TEMP    Temperature    1:180     1:173    1:19       ...
You would open your data file, if possible following the examples found in the Ferret Users Guide by following the index entry "ASCII data: reading, examples", and then the command to make the plot would be a FILL or SHADE command such as
yes? FILL/Z=0 temp, lon, lat
Then the plot will show both the data, and the shape of the curvilinear grid.

If you need help reading your data, please send more information showing the format of your ASCII file.


Srinivas Chamarthi wrote:
hello everybody!
I am new to ferret but attracted to its features. The user-friendly nature of the user groups
and the moderators kindness is welcoming.

I have a problem with curvilinear coordinate grid. I am having the data in 3D space, but the grid is 
curvilinear and its southern boundary is from 40E-120E but the northern boundary is 60E-85E. It
looks like a trapezium.
Many (not here on user group) have suggested to treat each lat-log position as a profile and interpolate
these profiles onto a regular grid. I am finding it a little difficult and also the data is not reproduced
to my satisfaction. I do not know what the command is doing and what algorithm it is using etc.

Can some one working with this type of problem help me out to draw the plots?!

thanks in advance.

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