Re: Retrieving point data from netCDF files

From: Sylvia Murphy (murphys AT cgd.ucar.edu)
Date: Fri Nov 05 2004 - 11:32:31 MST

  • Next message: Sylvia Murphy: "Re: ctrans"

    Don, you could use NCO to extract these points if all you want to do is
    output that info in antother netCDF file. If however you want to do
    something with these points/profiles like graph them, average them etc
    then NCL would work for you.

    both NCO and NCL use a form of coordinate subscripting. a means by which
    you can extract a specific dimension using the associated coordinate
    variable for that dimension rather than an array index.

    e.g.

      extract lat 20N and lon 265 from a 2D array:

      point = x({20},{265})

    this differs than extracting a random point:

      point = x(34,45)

    this only works if there are coordinate variables assoicated with the
    data. When a variable is read into NCL, and it has coordinate variables,
    that information is bundled with the data values. A feature that many
    netCDF users find indispensible.

    sylvia

    On Fri, 5 Nov 2004, Don Morton wrote:

    > I apologize if this is real elementary or off-topic, but
    > I "think" NCL might be what I'm looking for. I've
    > looked and looked on the web and can't find anything
    > that specifically addresses this, yet I'm sure it must
    > be a common requirement for many.
    >
    > I want to grab output files from WRF (netCDF) and
    > retrieve station data for a number of locations.
    > Essentially, I want to be able to plug in a lat/lon/elevation/time
    > and get the values for specified variables at these single points.
    > Ultimately, I'd compare these with observed data.
    >
    > I've gotten the impression that NCL is much like Unix in the sense
    > that it provides lots of tools that just need to be strung together
    > in the right way, but I'm not really sure where I'd start, and
    > I'm wondering if someone might be able to point me in the right
    > direction. Is NCL indeed the direction I want to be looking in,
    > or are there other more appropriate tools I might want to consider?
    >
    > If you haven't already figured it out, I know a little of what NCL is
    > all about, but haven't quite made the "plunge" yet and am wondering
    > if this might be the best "black hole" to jump into :)
    >
    > Thanks for any help,
    >
    > Don
    >
    > --
    > ** NOT ON CAMPUS UNTIL SPRING 2005 **
    >
    > **************************************************************
    > Don Morton http://www.cs.umt.edu/~morton/
    > Department of Computer Science The University of Montana
    > Missoula, MT 59812 | Voice (406) 243-4975 | Fax (406) 243-5139
    >
    > May your trails be crooked, winding, lonesome, dangerous, leading to the
    > most amazing view. May your mountains rise into and above the clouds.
    > -Edward Abbey, naturalist and author (1927-1989)
    >
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