From: Waqar Younas <vickyqau_at_nyahnyahspammersnyahnyah>

Date: Sun May 26 2013 - 01:26:26 MDT

Date: Sun May 26 2013 - 01:26:26 MDT

Hi everyone,

I have one question regarding calculating probability density functions for

observation and forecast. I chose Pacific North American index both for

observation and forecast. The data dimensions of my observation and

forecast are (120,88) and (120,88,27) where 120 are lead time, 88 are

number of predictions and 27 are ensemble members. I used this code to

calculate the pdfs

;***********************************************************

; pdf_1.ncl

;

; Concepts illustrated:

; - Generating univariate probability distributions

; - Generating PDFs of each sample distribution

; - Paneling two plots horizontally on a page

;***********************************************************

load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"

load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"

load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"

begin

a = obs ;;;; dimensions are 120,88

b = forecast ;;;;;;; dimensions are 120,88,27

ap = pdfx(a, 0, False) ; default number of bins

bp = pdfx(b, 0, False)

;------------------------------------------------

; Plot each PDF

;------------------------------------------------

nVar = 2

plot = new ( nVar, "graphic")

wks = gsn_open_wks ("ps","pdf")

res = True

res@gsnDraw = False

res@gsnFrame = False

res@xyLineThicknessF = 2

res@tiYAxisString = "PDF (%)"

plot(0) = gsn_csm_xy (wks, ap@bin_center, ap, res)

plot(1) = gsn_csm_xy (wks, bp@bin_center, bp, res)

resP = True

resP@txString = "obs and forecast pdfs"

resP@gsnPanelRowSpec = True ; tell panel what order to

plt

gsn_panel(wks,plot,(/1,2/),resP)

end

My question is how the function pdfx works because in the pdf1.ncl it is

not mentioned what dimension of x should and if x has more than 1 dimension

how it works (i.e. which dimension or it combines all dimensions)?

For forecast, the pdf should be at least calculated atleast for each lead

time by combining the predictions and ensemble members.

Thank you in advance.

-- Best Regards Waqar Younas PhD Candidate Natural Resources and Environmental Studies (NRES) University of Northern British Columbia (UNBC) Canada

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Received on Sun May 26 01:26:36 2013

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