Re: extracting nearest points

[Ansley Manke <ansley@xxxxxxxxxxxxx>]

Hi Nicolas,
Here are a couple of answers to a similar question from the Ferret
email archives.

http://ferret.pmel.noaa.gov/Ferret/Mail_Archives/fu_2000/msg00422.html

Hope this'll get you started.   -- Ansley Manke

Nicolas Schneider wrote:

> Dear ferret users
>
> My problem is hopefully a trivial one. I have output data (3D) from an
> atmospheric model on a cartesian grid. The lowest grid points are usually
> missing values, as this are grid points below ground and therefore don't have
> values (only atmospheric variables considered). However, the first points above
> grid aren't all on the same level as topography is not uniform. I would now like
> to extract the first point above topography. When I set the region to the first
> level (K=10) and the issue the command
>
> LET above = press[K=@CIA]
>
> I get the indices of the first points above topography at every xy-point of the
> grid. However, "above" ranges from 0 (here lowest level already is above ground)
> to 15. My problem is to extract the values at exactly these indices. I would
> like to do something like a SAMPLEK(temp, above), where "above" is a grid with
> the same dimensions as temp but with the respective index of K to extract at
> every xy-point. Does something like that exist as a predefined function in
> ferret?
>
> Thanks very much for your help
>
> Nick
>
> _____________________________________________________________
>
> Nicolas Schneider
> PhD Student
> University of Bern
> Institute of Geography
> Climatology & Meteorology
> Hallerstrasse 12
> CH-3012 Bern
>
> phone +41-31-631-8542
> fax   +41-31-631-8511
> email schneid@giub.unibe.ch
> _____________________________________________________________

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