Computation/
norm.pro
calculate the norm of vectors field located on Arakawa C-grid
norm
Calculation
result = norm(uu, vv, DIREC=DIREC, _EXTRA=_EXTRA)
Return value
a 2D (xy), 3D (xyz or yt), 4D (xyzt) array
Parameters
uu
in
required
Matrix representing the zonal coordinates (at U/V point) of a field of vectors
A 2D (xy), 3D (xyz or yt), 4D (xyzt) or a structure readable by
litchamp and containing a 2D (xy), 3D (xyz or yt), 4D (xyzt) array.
Note that the dimension of the array must suit the domain dimension.
vv
in
required
Matrix representing the meridional coordinates (at V/U point) of a field of vectors
A 2D (xy), 3D (xyz or yt), 4D (xyzt) array or a structure readable by
litchamp and containing a 2D (xy), 3D (xyz or yt), 4D (xyzt) array.
Note that the dimension of the array must suit the domain dimension.
Keywords
DIREC
't' 'x' 'y' 'z' 'xys' 'xz' 'yz' 'xyz' 'xt' 'yt' 'zt' 'xyt'
'xzt' 'yzt' 'xyzt' Direction on which do averages
_EXTRA
Used to declare that this routine accepts inherited keywords
Examples
To calculate the average of the norm of streams on all the domain
between 0 and 50:
IDL> domdef, 0, 50
IDL> res = norm(un, vn, dir = 'xyz')
Version history
Version
$Id: norm.pro 371 2008-08-07 09:32:02Z pinsard $
History
Sebastien Masson (smasson@lodyc.jussieu.fr)
9/6/1999
Known issues
Restrictions
The norm is calculated on points T. To do this calculation, we average
field U and V on points T before calculate the norm. At the edge of
coast and of domain, we can not calculate fields U and V at points T,
that is why these points are at value !values.f_nan.
When we calculate on a reduce geographic domain, field U and V have not
necessarily the same number of point. In this case, we recut U and V to
keep only common points. We profit of this to redo a domdef which redefine
a geographic domain on which fields U and V are extracted on same points
To know what type of array we work with, we test its size and dates
gave by time[0] and time[jpt-1] to know if thee is a temporal dimension.
Before to start norm, make sure that time and jpt are defined how
they have to!
Other attributes
Uses routines
cm_4mesh
cm_4data
cm_4cal
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