# [ncl-talk] calculating and plotting change in standard deviation and change of both skewness and kutosis at 99% percentile

Dennis Shea shea at ucar.edu
Wed Oct 30 10:08:57 MDT 2019

```Possibly:
(a) For each time period
(b) For each statistic,
(c) For each location or for all locations [45*90] sort into ascending
order and pick the highest 1%
--------
If you can make the file available, I can take a look.

Dropbox or ftp

ftp ftp.cgd.ucar.edu
anonymous
your_email
cd incoming
put zo_hist_1850-2005_ens_1-100.nc
quit

After successful file transfer, send me an email.

On Wed, Oct 30, 2019 at 9:16 AM Sri.durgesh Nandini-Weiss via ncl-talk <
ncl-talk at ucar.edu> wrote:

> Hello everyone,
>
> I'm attempting to calculating, and plot changes for extreme value from sea
> surface height from an ensemble outputs.
>
> For e.g i am trying to analyse the change between 1986-2006 and 2081-2100
> at the 99% percentiles from the ensemble from the change in statistics
> (mean,  standard deviation and  change of both skewness and kutosis). I
> adapted my script from extval_6.ncl
>
> Is the below the correct way?
>
> ;************************************************
> ; extvalv_6.ncl
> ;
> ; Concepts illustrated:
> ;   - Using extval_mlegev  and extval_gev
> ;   - Calculate basic statistics
> ;     - Basic statistics of the original sample
> ;     - Estimate GEV distribution parameters
> ;   - Creating a 'text' object to attach to a plot
> ;************************************************
>
>    fn  = "zo_hist_1850-2005_ens_1-100.nc" ; define filename [time | 1872]
> x [ens | 100] x [depth | 1] x [lat | 45] x [lon | 90]
>
>    in  = addfile(fn,"r")                                 ; open netcdf file
>    ts  = in->zo                                          ; read in variable
>    printVarSummary(ts)
>
> ;************************************************
> ;  calculate deviation from zonal mean
> ;************************************************
>    anom = dim_rmvmean_n_Wrap(ts,0)
>    printVarSummary(anom)
>
> ;***************************************************************
> ;--- "Normal" (conventional) statistical estimates for full sample
> ;***************************************************************
>
>    xStat4 = dim_stat4_n(ts, 0)  ; 1st 4 moments of original sample
>    printVarSummary(xStat4 )
>
>    xAvg   = xStat4(0)              ; original sample mean
>    xStd   = sqrt(xStat4(1))        ;    "     sample std dev
>    xSkew  = xStat4(2)              ; skewness; departure from symmetry
>    xKurt  = xStat4(3)              ; kurtosis; relative to a normal
> distribution
>    xLow   = min(ts)
>    xMed   = dim_median_n(ts,0)  ; median of original sample
>    xHi    = max(ts)
>
>
> ;***************************************************************
> ;--- PLOTS
> ;***************************************************************
>
>    wks  = gsn_open_wks ("pdf","ext6")                ; send graphics to
> PNG file
>
>    gsn_define_colormap(wks,"default")
>    plot = new(2, "graphic")
>
> ;************************************************
> ; Panel
> ;************************************************
>
>    resP                     = True                  ; modify the panel plot
>    resP at gsnMaximize         = True                  ; ps, eps, pdf
>    resP at gsnPanelMainString  = "River Flow Rate"     ; use this for NCL
> V6.4.0 and later
>    resP at txFontHeightF       = 0.020
>    gsn_panel(wks,plot,(/1,2/), resP)                ; now draw as one plot
>
> ;***************************************************************
> ;--- create histogram for the original sample
> ;***************************************************************
>
>    resh = True
>    resh at gsnDraw      = False
>    resh at gsnFrame     = False
>    resh2gsnHistogramNumberOfBins = 11
>
>    resh at gsFillColor  = "green"
>    resh at tiMainString = "SSH: N="+ntim
>    plt_hist          = gsn_histogram(wks, ts ,resh)
>
> ;***************************************************************
> ;--- text object original sample statistics; place on histogram
> ;***************************************************************
>
>    txres                       = True
>    txres at txFont                = "helvetica-bold"
>    txres at txFontHeightF         = 0.0150
>    textSample  = (/"  Mean="+sprintf("%5.1f", xAvg) +"~C~"+  \
>                    "   Std="+sprintf("%5.1f", xStd) +"~C~"+  \
>                    "  Skew="+sprintf("%5.2f", xSkew) +"~C~"+  \
>                    "  Kurt="+sprintf("%5.2f", xKurt) +"~C~"+  \
>                    "  xLow="+sprintf("%5.1f", xLow) +"~C~"+  \
>                    "  xMed="+sprintf("%5.1f", xMed) +"~C~"+  \
>                    "   xHi="+sprintf("%5.1f", xHi ) /)
>    txBoxSample  = gsn_create_text(wks,textSample, txres)
>
>    amres  = True
>    amres at amParallelPosF   =  0.30             ; move legend to the right
>    amres at amOrthogonalPosF = -0.10             ; move the legend up
>    annoSample = gsn_add_annotation(plt_hist, txBoxSample, amres)  ; Attach
> string to plot
>
>    draw(plt_hist)
>    frame(wks)
>
>
>
> the change in statistics--
>  Sri Nandini-Weiß
> Research Scientist
>
> Universität Hamburg
> Center for Earth System Research and Sustainability (CEN)
> Cluster of Excellence 'Climate, Climatic Change, and Society' (CLICCS)
>
> Bundesstrasse 53, 20146 Hamburg
> Tel: +49 (0) 40 42838 7472
>
> _______________________________________________
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