[ncl-talk] cross_corr_query

[Kunal Bali]

I have the data over the central arabian sea with the time steps = 31.

With the given script, could you please let me know am I doing the
corss-correlation in a wright way

;*************************************************
; corel_3.ncl
;
; Concepts illustrated:
;   - Calculating a two-dimensional correlation in time
;   - Reordering an array
;   - Copying attributes from one variable to another
;   - Copying coordinate arrays from one variable to another
;
;************************************************
;
; These files are loaded by default in NCL V6.2.0 and newer
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
;************************************************
; open file and read in variable
;***********************************************
  in1  = addfile("/media/Local Disk/NPL2/cross_corr_spatial/var1.nc","r")
  in2  = addfile("/media/Local Disk/NPL2/cross_corr_spatial/var2.nc","r")


  tmp1 = in1->DUD
  tmp2 = in2->SRT
;************************************************
; reorder to get time as right most dimension
;***********************************************
  ts1 = tmp1(latitude|:,longitude|:,time|:)
  ts2 = tmp2(latitude|:,longitude|:,time|:)
;************************************************
; calculate cross correlations
;************************************************
  maxlag = 3                                 ; set lag
; note, the max lag should not be more than N/4

  ccr = esccr(ts1,ts2,maxlag)                   ; calc cross correlations

; copy meta data and coordinate variables using contributed functions
  copy_VarAtts(ts1, ccr)
  copy_VarCoords_1(ts2,ccr)
;************************************************
; plot the correlations
;************************************************
;************************************************
 ;---Open workstation and change color map
  wks_type = "png"
  wks        = gsn_open_wks(wks_type, "CCR_2_lag3")
;************************************************


  res                      = True                ; make plot mods
  res at gsnLeftString     = ""
  res at gsnRightString    = ""
  res at gsnAddCyclic       = False
  res at cnFillOn             = True                ; turn on color
  res at cnFillPalette        = "BlWhRe"            ; set color map

  res at cnLinesOn            = False               ; turn off contour lines
  res at cnLevelSelectionMode = "ManualLevels"      ; manually set cn levels
  res at cnMinLevelValF       = -1.                 ; min level
  res at cnMaxLevelValF       =  1.                 ; max level
  res at cnLevelSpacingF      = .1                  ; contour level spacing

  lag                      = 3
  res at tiMainString         = "Correlations at lag "+lag

  res at mpMinLonF = 59.8
  res at mpMaxLonF = 69.8
  res at mpMinLatF = 16.5
  res at mpMaxLatF = 25.0

  plot = gsn_csm_contour_map(wks,ccr(:,:,lag),res)
;************************************************
end



Kunal Bali
Research Scholar
Radio & Atmospheric Science Division
CSIR - National Physical Laboratory
New Delhi - 110012
India





On Fri, Sep 9, 2016 at 12:28 PM, Will Hobbs <will.hobbs at utas.edu.au> wrote:

> Kunal
>
>
>
> At least one of the data points in the arrays that you are correlating has
> every single value as ‘missing’ or the same value throughout. This usually
> occurs if your data includes some masked regions, e.g. ocean data with a
> spatial domain that includes land.
>
>
>
> Another possible valid condition would be precipitation data where one or
> more data points has been in drought for the entire time period, i.e. P = 0
> throughout
>
>
>
> If you’re expecting you input data to include masked areas or similar
> physical conditions then it’s probably nothing to worry about (although
> that doesn’t mean you shouldn’t check). If you’re not expecting any missing
> values in your data then you may have a problem with your input arrays –
> but that’s not really an NCL problem.
>
>
>
> Will
>
>
>
>
>
>
>
> *From: *<ncl-talk-bounces at ucar.edu> on behalf of Kunal Bali <
> kunal.bali9 at gmail.com>
> *Date: *Friday, 9 September 2016 at 4:46 PM
> *To: *"ncl-talk at ucar.edu" <ncl-talk at ucar.edu>
> *Subject: *[ncl-talk] cross_corr_query
>
>
>
> Dear NCL users,
>
> I am trying to plot the cross-correlation map. While doing this, I have
> baeen facing one error
>
> warning:esccr: Non-fatal conditions encountered: all missing or constant
> values
>
> Could anyone please let me know, how to fix it.
>
> Regards
>
> Kunal Bali
>
>
>
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