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mjo_spectra_season

Calculates seasonal spectra via segment averaging as defined by the US-CLIVAR MJO diagnostics website.

Available in version 5.1.0 and later.

Prototype

load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"        ; These three libraries are automatically
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"         ; loaded from NCL V6.2.0 onward.
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"     ; No need for user to explicitly load.

load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/diagnostics_cam.ncl" ; Still need to load this library.

	function mjo_spectra_season (
		x    [*][*][*] : numeric,  
		date       [*] : integer,  
		wy         [*] : numeric,  
		seasonName [1] : string,   
		opt        [1] : logical   
	)

	return_val  :  array [4][dimsizes(time)/2]

Arguments

A three-dimensional variable array. Nominally: (time,lat,lon).

date

An integer array containing the date as "YYYYMMDD".

A one-dimensional array containing the latitudinal weights associated with x.

opt

If opt=False, the function will operate under default mode regardless of any attributes associated with the variable.

If opt=True, then the following attributes, associated with opt, may be used to alter the default behavior.

opt@detrend=True: Entire series will be detrended. Default: opt@detrend=False.

opt@detrend_seg: If this attribute is present, each segment will be detrended. Default: False

opt@taper_seg: If present, each segment will be tapered. prior to computing the spectra. Typically, opt@taper_seg=0.1 [10% of segment length]. Default: no tapering performed.

opt@smooth_seg: If present, each segment will be smoothed using a running average of length opt@smooth_seg. Default: No smoothing performed.

Return value

The return variable will be a scalar containing the degrees of freedom. Associated with the return variable are the following attributes:

bw - band-width

spcx - 1D array containing the segment averaged spectra.

frq - 1D array containing the frequencies.

vari - average of each segment's input variance

xlag1 - average lag one day autocorrelation

Description

This function can be called as a stand-alone function but, generally, is meant to be invoked by the mjo_spectra procedure.

MJO CLIVAR specifies to use no detrending, tapering or smoothing. The seasons are specified as follows:

      winter (segment) starts Nov 1  [180 days]
      summer (segment) starts May 1  [180 days]
      annual (segment) starts Jan 1  [365 days]

Examples