Fwd: [ncl-talk] Lat/Lon Question

I thought (but could not find) a JIRA ticket on this. I thought DaveB
mentioned something on this. Maybe related to GRIB???? I may be mistaken
but thought I bring it up.

D

---------- Forwarded message ----------
From: Rick Brownrigg <brownrig@ucar.edu>
Date: Wed, Jul 9, 2014 at 11:03 AM
Subject: Re: Lat/Lon Question
To: Greg Garrett - NOAA Federal <greg.garrett@noaa.gov>
Cc: ncl-talk <ncl-talk@ucar.edu>


Hi Greg,

I'm not aware of a means to do this from within NCL. If I had to do it,
I'd use the Proj4 cartographic projection library, which would entail:

- writing the X/Ys to a temp file,
- issue a system() call with a proper command-line containing the L.C.
projection details to the "proj" command, which would then read the temp
file and write a new file containing lat/lons
- read the lat/lon

Its a bit clunky, but not too hard *if* you already have Proj4 and are
familiar with it (http://trac.osgeo.org/proj/)

Hope that helps...
Rick



On Wed, Jul 9, 2014 at 9:51 AM, Greg Garrett - NOAA Federal <
greg.garrett@noaa.gov> wrote:

> I am working with a Lambert Conformal projected dataset with GeoX and GeoY
> x and y coordinates (excerpt below). There are no latitude or longitude
> coordinates.
> Can anyone tell me if it is possible to compute lat/lon from the x,y, and
> projection information and if so, how?
>
> Thanks,
>
> Greg
>
>
> x = 1799
> y = 1059
> variables:
> integer LambertConformal_Projection ( ncl_scalar )
> long_name :
> grid_mapping_name : lambert_conformal_conic
> latitude_of_projection_origin : 38.5
> longitude_of_central_meridian : 262.5
> standard_parallel : 38.5
> earth_radius : 6367470
> _CoordinateTransformType : Projection
> _CoordinateAxisTypes : GeoX GeoY
>
> float x ( x )
> units : km
> long_name : projection_x_coordinate
> standard_name : projection_x_coordinate
> _CoordinateAxisType : GeoX
>
> float y ( y )
> units : km
> long_name : projection_y_coordinate
> standard_name : projection_y_coordinate
> _CoordinateAxisType : GeoY
>
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Received on Wed Jul 09 05:30:57 2014