Re: [ferret_users] picking up average value along track

[Mick Spillane <mick.spillane@xxxxxxxx>]

Here is something that might help, at least in a 2-D situation. There it seems like what you have is a masking problem - to identify cells that are "close" to the track.  The attached script assumes that you have a set of coordinate pairs (lon,lat) that define the track.  Then, defining a distance in km to the left and right of the track that you want to include, the script generates the lon,lat coords of tracks offset to the left and right of the central one.

Next, if you reverse one of those new tracks and append its coords to the other, you have the definition of a polygon. Finally the mask will be the cells that fall within that polygon -- see earlier posts regarding "points inside a polygon".

If the track definition is fine enough, spaced closer than the data grid, you could alternately set up a mask selecting grid cells whose minimum distance from a point on the track is less than some amount. This approach would work too if what you need is the average within a specified horizontal distance, and depth range about a 3-D track as you question seems to indicate.

Good luck,

  Mick
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On Thu, Jun 28, 2012 at 10:00 AM, golla nageswararao <ezeenag4u@xxxxxxxxx> wrote:

Hi all,
 Is there any method to pick up an average value along a described track. Suppose I am having a gridded temperature data (.25°x.25°) over Indian Ocean, then if I draw a line arbitrarily. For picking up the data along the track in ferret there is an option samplexy command. Suppose if I want to pick up the average data in the search radius of the grid resolution (above, below, left, right sides of values to be averaged), is there any option in ferret?

Thanks in advance.

--
With Best regards,
G.NageswaraRao,

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