Re: [ferret_users] extracting boundary information from a masked file

["Paulo B. Oliveira" <pboliveira@xxxxxxx>]

Dhirendra,

Since you're dealing with 2D fields it will be easier to build a land mask from 2D variables than a 1D lat/lon boundary. 

You say that your values are over land only, are they 1D or 2D ? 

If your data is 1D, first build a 2D field using a 'scat2grid*' function (do list them, try: yes? sh fun scat2grid* ), then it should be straightforward to build a land mask from your own data (let msk = if your_var then 1).

The attached script illustrates how 2D var masking works. 

Paulo
----------------
On Tue, 2015-10-20 at 14:05 +0530, Dhirendra Kumar wrote:
>     Dear Ferret Community
>     
>     
>     I have a netcdf file which has got the values over land regions only. Is there any way through which I can extract the boundary information (list of Latitude and longitude of boundary)out of it, so that other file could be masked over the same region.
>     
>     Please help....
>     
>     Any lead is appreciated.
>     
>     Sincerely
>     Dhirendra
>     
>     
>     
>     -- 
>     ========================================
>     Dhirendra Kumar
>     UGC-JRF 
>     
>     School of Environmental Sciences, JNU
>     
>     New Delhi (India)
>     Contact: +91 9910778043
>     Alternate email: dhirendra.cub@xxxxxxxxxxx
>     =========================================

Attachment: topo_land_ocean.png
Description: PNG image

 ! NOAA/PMEL TMAP
 ! FERRET v6.93 (PyFerret 1.1.0)
 ! Linux 2.6.35.14-106.fc14.i686 - 12/05/14
 ! 20-Oct-15 10:40     

use etopo05

let land = if rose ge 0 then 1
let ocean = if rose lt 0 then 1

set reg/y=5:35/x=65:95

set win/asp=0.5

set viewp left; shade rose*land; go land_detail
set viewp right; shade rose*ocean; go land_detail

frame/file=topo_land_ocean.png

quit