[ncl-talk] Question about Spectral Analysis(computation of variance)

[Lyndon Mark Olaguera]

Hi All,

I'm trying to perform spectral analysis using the specx_anal function in
ncl.
I'm getting a variance around 1000 near the zero mark.I dont know if I'm
missing a step prior to performing the spectral analysis. I would like to
ask for any suggestions on how can I improve this.


Attached are the data set and script.

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

begin
filename = "type1_clim.csv"
lines    = asciiread(filename,-1,"string")
data     = lines(1:)
rain    = tofloat(str_get_field(data,10,","))

d = 1
sm = 12
pct = 0.10

spec= specx_anal(rain,d,sm,pct)
printVarSummary(spec)

wks  = gsn_open_wks("png","test_fldmean")             ; Opens a ps file
res = True
res at tiMainString = "Type1_Spectrum"                     ; title
f = spec at frq
res at tiXAxisString = "Frequency (cycles/day)"  ; xaxis
res at tiYAxisString = "Variance"                       ; yaxis

splt = specx_ci(spec, 0.05, 0.95)

res at xyLineColors        = (/"foreground","green","blue","red"/)
plot = gsn_csm_xy(wks,f,splt,res)     ; create plot
end

I'll appreciate any help.

Many thanks,

Lyndz
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