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Re: Point Observations from NARR output [message #75755 is a reply to message #75752]

Thu, 07 April 2011 15:06

Kenneth P. Bowman
Messages: 585
Registered: May 2000

Senior Member

In article
<ae2b9885-d9aa-42b6-b3d5-6418072f19e6@f11g2000vbx.googlegroups.com>,
"B.J. Baule" <guitarplayer_101@comcast.net> wrote:

> Hello all,
>
> This is probably a really simple problem however my inexperience
> with IDL has left me baffled. I'm relatively new to IDL programming
> and have a question regarding getting grid point values from NARR
> reanalysis output. I can get the data to open, read in, and make a
> map. However, I would like to get point observations from the
> reanalysis data set (Ex. July Temperature for Barrow, AK Lat:
> 71.2905556 Lon:-156.7886111).

I suggest that you compute the great circle distance between
Point Barrow and all of the longitude-latitude points on the
NARR grid. Then find the minimum. You only have to do this once.
That will tell you which grid point is closest to Barrow.

If you insist on interpolating to Barrow, you will have to
do that in Cartesian coordinates on the Lambert conformal grid.
Probably not worth it, in my opinion.

To compute great circle distance use MAP_2POINTS. (One of my
nominations for least-intuitive and least-mnemonic routine name
in IDL.) You will spend half an hour trying to get all of
the units and keywords right, but it does work.

Ken Bowman

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[Message index]

		Re: Point Observations from NARR output By: B.J. Baule on Thu, 07 April 2011 17:11
		Re: Point Observations from NARR output By: Kenneth P. Bowman on Thu, 07 April 2011 15:06
		Re: Point Observations from NARR output By: B.J. Baule on Thu, 07 April 2011 13:31

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