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[THREDDS #AYF-864661]: a simple question about the NAM_Alaska_45km model

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  • Subject: [THREDDS #AYF-864661]: a simple question about the NAM_Alaska_45km model
  • Date: Mon, 11 Jan 2010 16:08:20 -0700
Larry,

The Grid Definition Section of a Grib file have a COMPONENT FLAG to designate 
how the values are calculated. Either it's grid relative or easterly Northerly.
From the grib documentation:
5
0       Resolved u and v components of vector quantities relative to easterly 
and northerly directions
1       Resolved u and v components of vector quantities relative to the 
defined grid in the direction
        of increasing x and y (or i and j) coordinates, respectively.

For the Alaska_45km conduit file, the VectorComponentFlag = 1 so the values are 
calculated at the center of the node.

Here are some urls:
http://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_table3-3.shtml
http://www.meted.ucar.edu/nwp/model_structure/navmenu.php?tab=1&page=1.4.0  // 
have to create user and login

The VectorComponentFlag = 0 is usually found on staggered grids. 

Robb...

 

Ticket Details
===================
Ticket ID: AYF-864661
Department: Support THREDDS
Priority: Normal
Status: Open