[Wrf-users] storing location info in geo files

David Bryan davidstephenbryan at yahoo.com
Tue Apr 26 10:11:39 MDT 2011

I'm trying to understand how WRF geo files store location information.
For instance, I recently made a 49x49 geo file and opened it in Panoply.  I 
looked at CLAT (and then CLONG) under the Array tab (numeric values, not 
visualized).  What I found was a 48x48 array of lat-longs.  

My questions:
1.  Do WRF's geo files store location information (lat-longs) at the midpoint 
between grid points?
2.  This reminded me of the illustration of coarse grid in the "Nesting in WRF" 
document (p. 13 here:  
http://www.mmm.ucar.edu/wrf/users/tutorial/201101/WRFNesting.pdf).  In the 
illustration, wind speed components, u & v, were stored on the grid point (ie, 
at the perimeter of each "cell" assuming a 5x5 grid), while temperature, T (or 
theta), was stored at the midpoint between grid points (ie, in the center of 
each "cell").  If that illustration is accurate (and my understanding of it 
correct), does that mean that each T value is associated with a CLAT-CLONG 
pair?  Is there one less row and one less column of T data per grid (ie, in my 
case 48x48)?

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