# [ncl-talk] RATIO in Taylor Diagram

Dennis Shea shea at ucar.edu
Thu Sep 17 12:33:54 MDT 2015

```See attached: Hopefully that will answer your question.

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Good Luck
D,

On Mon, Sep 14, 2015 at 8:14 PM, Vanúcia Schumacher
<vanucia-schumacher at hotmail.com> wrote:
> Dear users,
>
> I'm confused with the calculation of RATIO (normalized root-mean-saquare
> (RMS) differences), relation to Taylor Diagram,  the comments that I have
> read here in the group, it was suggested calculated in 3 ways:
>
> 1) Use of the function:   dim_rmsd
>
> or
>
> 2) RATIO
> ; temporal variance at each grid point [local]
>
> ;   vref_var_T = dim_variance_n(rdata, 0 ) ; (lat,lon)
> ;   vcase_var_T = dim_variance_n(cdata, 0 )
>
> ;                 ; wgted areal *local* temporal variance
>
> ;   wvar_ref_T = sum(wgt_S*vref_var_T)/sumwgt_S
> ;   wvar_case_T = sum(wgt_S*vcase_var_T)/sumwgt_S
>
>                  ; sqrt of ratio of spatially weighted variances
>
> ;   wvar_ratio_T = (wvar_case_T/wvar_ref_T)^0.5
>
> I did not understand what would that sumwgt_S ?
>
> or 3) more explicitly, for xc and xo on the same grid: wgtc=wgto
>
> ;         wgtc  = conform_dims(dimsizes(xc), gw, 0)    ; make 2d for gw[*]
> ;         xavgc = sum(wgtc*xc)/sum(wgtc)               ; control centered
> mean
> ;         xavgo = sum(wgtc*xo)/sum(wgtc)
>
> ;     (b) compute the sum of the centered area weighted variances.
>
> ;         dc2   = sum(wgtc*(xc-xavgc)^2)               ; control ; centered
> ;         do2   = sum(wgtc*(xo-xavgo)^2)
> ;         rat   = sqrt(do2/dc2)
>
> xc and xo is the variance or datasets?
>
>
> I would like to know the step by step to correct this calculation RATIO, if
> someone can help me, please.
>
> Thanks
>
>
>
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