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Re: removing value in land



Andrea,
Yes.  Look up "masking, for transformations on irregular regions"  in the
index to the Ferret Users guide (Chapter 3, Sec 2.4.2, "Transformations
applied to irregular regions").  You will need a topography data set (see
Mick's  message a few minutes ago).  Your data and the topography data
needs to be on the same grid.

Then set up a mask something like this, where elev is the topography data.

yes?  LET  ocean_mask  =  IF  elev LT  0 THEN 1
yes?  LET  masked_var =  IF ocean_mask THEN my_var ELSE bad_value

where my_var is a variable you want to work with,  and you've defined bad_value
to be the value of the missing-data flag for your data.

yes?  SHADE masked_var   !  to test what you have done

Ansley Manke

andreast@usp.br wrote:

Hello!

I have some data that have value over land, but I would like to make some
analysis only over oceans.

Does anyone know how can I put 'missing value' over land?

Thanks,

Andrea S. Taschetto

--
Ansley Manke  Pacific Marine Environmental Laboratory  Seattle WA  (206)526-6246
 


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