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Computation/

div.pro

compute the horizontal divergence of a vectors field located on Arakawa C-grid.

topdiv Calculation

result = div(uu, vv, DIREC=scalar string, MILLION=scalar: 0 or 1, _EXTRA=_EXTRA)

Return value

the divergence of the input data (with the same size) located at T point (see restrictions).

Parameters

uu       

Matrix representing the zonal coordinates (at 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 (at 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

MILLION        type: scalar: 0 or 1 default: 0

Activate to multiply returned array by 1.e6

_EXTRA       

Used to declare that this routine accepts inherited keywords

Examples

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

Version history

Version

$Id: div.pro 378 2008-08-12 12:35:46Z 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_4mesh

Statistics

McCabe cyclic 55
McCabe essential 1
McCabe modular design 1
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