calcMonAnomLLT

Calculates monthly anomalies by subtracting the long term mean from each point (lat,lon,time version)

Prototype

load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"  ; This library is automatically loaded
                                                             ; from NCL V6.2.0 onward.
                                                             ; No need for user to explicitly load.

	function calcMonAnomLLT (
		x     [*][*][*] : numeric,  
		xAve [*][*][12] : numeric   
	)

	return_val [dimsizes(x)] :  numeric

Arguments

A three-dimensional array of any numeric type. Dimensions must be lat, lon, time. The time dimension must be a multiple of 12.

A three-dimensional array equal to the monthly averages of x. The leftmost two dimensions are lat and lon, while the rightmost must be of size 12.

Return value

An array of the same size and type as x.

Description

Calculates climatological anomalies by subtracting the long term mean from each point. Assumes monthly data. If the input data contains metadata (e.g. coordinate variables and attributes), these will be retained.

See Also

calcMonAnomLLLT, calcMonAnomTLL, clmMonLLT, clmMonLLLT, clmMonTLL, clmMonTLLL

Examples

Example 1

;====================================
; Read data
;====================================
  in = addfile("zzp300.monthly.1948_1998.nc","r")
  tser_t  = in->ZZP({25:},:,:)
  tser    = tser_t(time|:,lat|:,lon|:)    ;1948-1998  (612)

  dimice=dimsizes(tser)
  ntim2=dimice(0)
  nlat2=dimice(1)
  mlon2=dimice(2)

;====================================
; Calculate the JFM Clim.
;====================================
  temptser = tser(lat|:,lon|:,time|:)
  jfmtemp  = temptser(:,:,:50)
  jfmclim  = temptser(:,:,0) 
  soi1     = runave(temptser,3,0)
  jfmtemp  = (/ soi1(:,:,1:ntim2-1:12) /)  
  jfmclim = (/ dim_avg(jfmtemp) /)
;====================================
; Calculate and Remove the Long-Term 
; Monthly Means, + compute JFM Avg.
;====================================
  slp_clm = clmMonLLT (temptser)             ;Calculate LTMM's
  newslp  = calcMonAnomLLT(temptser,slp_clm) ;Calculate Anomalies from Means