[ncl-talk] How to get explained variance from spectra

[Dennis Shea]

As notes in the *specx_anal*
<http://www.ncl.ucar.edu/Document/Functions/Built-in/specx_anal.shtml>
documentation:
-====

These spectra have been normalized so that the area under the curve:

(*spcx*(0)+*spcx*(*N*/2-1))*(df/2) + SUM{*spcx*(1:N/2-2)*df}

equals the variance of the detrended series, where df=(1/*N*)=frequency
spacing.

The units are variance/(unit frequency interval).

====

You know the frequencies corresponding to  5-to-10 days.


5-to-10day variance:   var_510 = SUM{*spcx*('f5->f10')*df}


fractional_variance = var_510/total_variance




On Thu, Sep 16, 2021 at 2:39 AM Lyndz via ncl-talk <
ncl-talk at mailman.ucar.edu> wrote:

> Dear NCL-experts,
>
> I have a sample data that I attached here and below is the script that I
> used to plot the spectra.
>
> I found significant peaks between 5-10 (days).
>
> I would like to ask how to estimate the fractional variance of
> total rainfall variability explained by this 5-10 days ISO. Im not sure if
> this can be estimated from the spectra. If not, any suggestions on how to
> do this NCL?
>
>
> -Lyndz
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