[CF-metadata] U and V "grid relative" velocities

From: Rich Signell <rsignell>
Date: Mon, 22 Nov 2004 08:42:38 -0500

All,

The U and V staggered velocities computed in Arakawa C grid
models are oriented relative to the grid in the "I" and "J"
directions, not true east and north (unless the grid happens to
be oriented N/S, E/W). On a general curvilinear orthogonal grid,
the orientation of these components change at every grid cell.
                                                                                

It seems the proper way to specify this in CF is through the
use of
                                                                                

u:standard_name="sea_water_x_velocity"
v:standard_name="sea_water_y_velocity",
                                                                                

Is this right?
                                                                                

One could alternatively have this be inferred for U and V
variables that have Arakawa C grid defined (via the proposed
"grid" attribute and "grid_type"="Arakawa C")
                                                                                

-Rich

-- 
Richard P. Signell           rsignell at usgs.gov
U.S. Geological Survey       Phone: (508) 457-2229
384 Woods Hole Road          Fax:   (508) 457-2310
Woods Hole, MA  02543-1598  

Received on Mon Nov 22 2004 - 06:42:38 GMT