# fluxEddy

Calculates time averaged eddy flux quantities.

**Note:** This function is only available in version 4.1.1 of
NCL. If your site is licensed for version 4.1, then you can get
version 4.1.1 for free. To get version 4.1.1 of NCAR Graphics
software, please contact your site representative. If you don't know
who your site representative is, then send email to ncarginf@ucar.edu or call (303)
497-1201.

## Synopsis

function fluxEddy(
x : float,
y : float
)

## Arguments

*x*
- A float array with one or more dimensions. The rightmost
dimension must be "time". Missing values should be indicated by
*x*@_FillValue. If *x*@_FillValue is not set, then the NCL
default (-999) will be assumed.
*y*
- A float array with one or more dimensions. It must have the same
dimensions as
*x*. Missing values should be indicated by
*y*@_FillValue. If *y*@_FillValue is not set, then the NCL
default (-999) will be assumed.

## Description

`fluxEddy` returns a float array of the same dimensionality as
its input arrays with the last dimension omitted. The resulting
quantities are computed in one pass. The approach used is let x=X+x'
and y=Y+y' where X and Y are time averages, then x'y' = ave{x*y} -
X*Y. Missing values are allowed.

## Example 1

Let *x* and *y* be dimensioned *nlat* x *mlon* x
*ktimes* (*nlat*=64, *mlon*=128, *ktimes*=90):
xpyp = fluxEddy (x,y) ; xpyp=x'y' will be an nlat x mlon array

## Example 2

Let *u* and *v* be dimensioned *ntimes* x *klev* x
*nlat* x *mlon* with named dimensions "time" , "lev" , "lat"
, "lon". Then:

upvp = fluxEddy (u(lev|:,lat|:,lon|:,time|:), v(lev|:,lat|:,lon|:,time|:))

*upvp* will be a 3-dimensional array dimensioned *klev* x
*nlat* x *mlon*.

## Example 3

To calculate the eddy variance of a quantity *z*. (I.e. ave{z'z'}):

zpzp = fluxEddy (z,z)

or

zpzp = fluxEddy (z(lev|:,lat|:,lon|:,time|:), z(lev|:,lat|:,lon|:,time|:))

depending upon the dimension order.

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* $Revision: 1.3 $ $Date: 1999/03/22 20:49:09 $ *