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[aprssig] future problems with NWS radar images?

AE5PL Lists HamLists at ametx.com
Mon Mar 28 22:59:37 UTC 2005

The current radar gifs are done using a stereographic projection
centered on the radar site with an Earth radius of 6371.2 km.  This is
done this way, I would guess, because the dots can be charted using
simple polar coordinates instead of doing lat/lon translations.  Yes,
this does make some difference in plotting, especially in the outer half
of the coverage area.

As to their new graphics, I have not worked with them yet to get the
full information on how they are being projected into the image.


Pete Loveall AE5PL
mailto:pete at ae5pl.net 

> -----Original Message-----
> From: Tyler Allison
> Posted At: Monday, March 28, 2005 4:31 PM
> Subject: Re: [aprssig] future problems with NWS radar images?
> > Does anyone else have any information as to where the NWS 
> is going here?
> The original radar data, as provided to the research 
> community via the Unidata IDD Cooporative, is supposedly in 
> Lambert Conformal. Im not up on my projections but maybe 
> that's the "spherical" projection they are talking about?
> Instead of using the GIF images why not grab the radar data 
> raw (via FTP) and convert to image format yourself using 
> Gempak? That way you can control the projection.

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