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Computation/

div.pro

compute the horizontal divergence of a vectors field

div Calculation

result = div(uu, vv, DIREC=scalar string)

Return value

the divergence of the input data (with the same size)

Parameters

uu       

Matrix representing the zonal coordinates (U point) of a field of vectors A 2D (xy), 3D (xyz or yt) or a structure readable by litchamp and containing a 2D (xy), 3D (xyz or yt) array (4D case is not coded yet). note that the dimension of the array must suit the domain dimension.

vv       

Matrix representing the meridional coordinates (V point) of a field of vectors A 2D (xy), 3D (xyz or yt) or a structure readable by litchamp and containing a 2D (xy), 3D (xyz or yt) array (4D case is not coded yet). note that the dimension of the array must suit the domain dimension.

Keywords

DIREC        type: scalar string

Use if you want to call moyenne or grossemoyenne after the div computation (stupid ?) with a mean done in the DIREC direction

Examples

 IDL> @tst_initorca2
 IDL> plt, div(dist(jpi,jpj), dist(jpi,jpj))

    

Version history

Version

$Id: div.pro 268 2007-08-24 14:07:01Z pinsard $

History

Guillaume Roullet (grlod@ipsl.jussieu.fr): creation; spring 1998 Sebastien Masson (smasson@lodyc.jussieu.fr) adaptation to work with a reduce domain; 12/1/2000

Known issues

Todo items

code the 4D case

Restrictions

- Works only for Arakawa C-grid. - UU must be on U grid, VV must be on V grid - 4D case is not coded yet - the common variable jpt is used to differ xyz (jpt=1) and xyt (jpt=1) cases. - U and V arrays are cut in the same geographic domain. Because of the shift between T, U, V and F grids, it is possible that these two arrays do not have the same size and refer to different indexes. In this case, arrays are re-cut on common indexes. To avoid these re-cuts, use the keyword /memeindice in domdef - When computing the divergence, we update, vargrid, varname, varunits and the grid position parameters (firstxt, lastxt, nxt, firstyt, lastyt, nyt). - points that cannot be computed (domain boundaries, coastline) are set to NaN

Other attributes

Uses routines

cm_4cal cm_4data cm_4mmesh

 


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