Tie point for grid coordinates

[Ramon Solano]

Hello all.

When defining the tie coordinates for GrADS grids (XVAR and YVAR),
what position is required? Pixel center coordinates, UL corner, LL
corner?  This is not trivial for coarse data sets, mainly when working
with more than one for correlation purposes.

All I could find was that  "..indicates the longitude at grid point
X=1" (for XVAR but same for YVAR).

Thanks,
Ramon
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Ramon Solano, Research Specialist
Terrestrial Biophysics and Remote Sensing Lab.
Dept. of Soil, Water and Environmental Sciences
The University of Arizona