Difference between revisions of "How to interpret WRF variables"

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==Grid==
 
==Grid==
  
coordinates, orientation, U, V, W points
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[[File:Wrfgrid.png|250px]]
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Grids in WRF are logically rectilinear. Variables for WRF cell indexed '''(i,j,k)''' can be located at one of 4 possible point. You can tell where by looking at the WRF registry or the attributes of [[NetCDF]] files, which WRF uses as I/O format. You can also tell by the fact that staggered variables have the staggered dimension larger by one, since there needs to be variable at the last boundary face.
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* at the center of the cell - theta points, not staggered
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* at the center of the left face - U point, staggered in X
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* at the center of the front face - V point, staggered in Y
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* at the center of the bottom face - W point, staggered in Z
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Scalar variables (such thermodynamical variables, hence the theta: temperature, pressure,...) generally live at theta-points. One exception is the geopotential, which lives at W-points. Components of the wind velocity vector U,V,W live at the corresponding points, hence their names.
  
 
==Elevation==
 
==Elevation==

Revision as of 21:54, 7 August 2010

Grid

Wrfgrid.png

Grids in WRF are logically rectilinear. Variables for WRF cell indexed (i,j,k) can be located at one of 4 possible point. You can tell where by looking at the WRF registry or the attributes of NetCDF files, which WRF uses as I/O format. You can also tell by the fact that staggered variables have the staggered dimension larger by one, since there needs to be variable at the last boundary face.

  • at the center of the cell - theta points, not staggered
  • at the center of the left face - U point, staggered in X
  • at the center of the front face - V point, staggered in Y
  • at the center of the bottom face - W point, staggered in Z

Scalar variables (such thermodynamical variables, hence the theta: temperature, pressure,...) generally live at theta-points. One exception is the geopotential, which lives at W-points. Components of the wind velocity vector U,V,W live at the corresponding points, hence their names.

Elevation

Temperature

Wind

Fire variables

Footnotes

</references>

See also

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