[ncl-talk] Spectral Analysis

[Dennis Shea]

The 'specx_anal' documentation clearly states that "Missing values are not
allowed. "
=================
Prototype

	function specx_anal (
		x    [*] : numeric,
		iopt [1] : integer,
		jave [1] : integer,
		pct  [1] : numeric
	)

	return_val <http://www.ncl.ucar.edu/Document/Functions/return_val.shtml>
[1] :  float or double

Arguments *x*

A one-dimensional array containing the data. Missing values are not
allowed.

==================

You could do

     aao at _FillValue = 0.0      ; change: _FillValue = 3.000000060858434e+33

     delete(aao at _FillValue)   ; delete recognition of _FillValue

There will be no error messages returned bu specx_anal and you will get
'numbers'

***BUT***

they are *not* the correct numbers. These 0-values will affect the
calculated spectrum.


=================

You must ****intelligently**** fill the _FillValue locations. Any old
numbers (eg: 0) will not accomplist this taks.


++++++++++++++++++++++++++++++++++++++++++++++++

Please become familiar with:  https://climatedataguide.ucar.edu/

Search fo AAO (or, equivalently, SAM)

https://climatedataguide.ucar.edu/climate-data/overview-climate-indices

https://climatedataguide.ucar.edu/climate-data/marshall-southern-annular-mode-sam-index-station-based

The latter has "Get Data (External)"  .... Click and get the data you want.








On Tue, Jan 17, 2017 at 3:52 AM, Kwesi Quagraine <starskykwesi at gmail.com>
wrote:

> Hello NCLers, I am currently trying to make a spectral analysis plot from
> a AAO indices (timeseries 1980-2016) netcdf file using the script
> (following spec_1 from ncl website) below and I get this error
> "fatal:specx_anal: 'x' cannot contain any missing values".
>
> [1] I have tried setting aao at _FillValue = 0 but to no avail
>
> Any help will be much appreciated.
>
>
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
>
> diri    = "/home/kwesi/Documents/Indices/"
>
> begin
>
>    in  =addfile(diri + "aao_anom.nc","r")                           ;
> open netcdf file
>    aao  = in->AAO
>
>   printVarSummary(aao)
>
>   d = 1
>   sm = 7
>   pct = 0.10
>
>   spec = specx_anal(aao,d,sm,pct)
>
>   wks  = gsn_open_wks("ps","spec")                ; Opens a ps file
>
>    res = True                       ; no plot mods desired
>    res at tiMainString = "AAO"                   ; title
>    res at tiXAxisString = "Frequency (cycles/month)"  ; xaxis
>    res at tiYAxisString = "Variance"                  ; yaxis
>
>    plot=gsn_csm_xy(wks,spec at frq,spec at spcx,res)     ; create plot
> end
>
> printVarSummary(aao) gives;
> ​Variable: aao
> Type: double
> Total Size: 3552 bytes
>             444 values
> Number of Dimensions: 1
> Dimensions and sizes:    [time | 444]
> Coordinates:
>             time: [   0.. 443]
> Number Of Attributes: 4
>   long_name :    Antarctic Oscillation Index
>   units :    1
>   _FillValue :    3.000000060858434e+33
>   missing_value :    3.000000060858434e+33
> ​
>
> --
> Try not to become a man of success but rather a man of value-Albert
> Einstein
>
> University of Cape Coast|College of Agriculture and Natural Sciences|Department
> of Physics|
> Team Leader|Recycle Up! Ghana|Technology Without Borders|
> Other emails: kwesi.quagraine at ucc.edu.gh|kwesi.quagraine at teog.de|
> Mobile: +233266173582 <+233%2026%20617%203582>
> Skype: quagraine_cwasi
> Twitter: @Pkdilly
>
>
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