[ncl-talk] Area averaging not being done in patter_cor function.
Dennis Shea
shea at ucar.edu
Fri Apr 15 07:47:43 MDT 2016
I guess I do not understand the issue..
x(nlat,lon) and y(nlat,mlon) and weights, wgt(nlat,mlon). Assorted pattern
correlations are computed via
wgt = 1.0
ra = *pattern_cor*(x, y, wgt, 0) ; no weighting, centered
[1] If (say) you have 100 points all weighted 1.0: sumWGT=100
[2] sum(x*WGT) = sum(x); (nlat,mlon)
[3] xAvgArea = sum(x)/sumWGT ==> overall average for (say) 100 points
so no ... "if my weight is 1 it is simply the sum of the array not the area
average"
It is the overall average ... not the "sum if the array"
===
Maybe I am misunderstanding the issue.
On Fri, Apr 15, 2016 at 4:44 AM, Shilpa Malviya <shilpamalviya123 at gmail.com>
wrote:
> Hi,
>
> When we call pattern_cor function it then calls pattern_cor2 function to
> compute the pattern correlation. I n case of centered correlation area
> averaging is done , the code is as below
>
> sumWGT = sum(WGT)
> xAvgArea = sum(x*WGT)/sumWGT ; weighted area average
> yAvgArea = sum(y*WGT)/sumWGT
>
> xAnom = x - xAvgArea ; anomalies
> yAnom = y - yAvgArea
>
> if my weight is 1 it is simply the sum of the array not the area
> average.This may lead to wrong results.
>
> Is it because of this that when I perform centered averaging I get values
> of the order of 0.6 and when uncentered then 0.9.
>
> Regards,
> Shilpa Malviya
>
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