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wrf_user_unstagger

Unstaggers an input variable along a specified dimension.

Prototype

load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"      ; These two libraries are automatically
load "$NCARG_ROOT/lib/ncarg/nclscripts/wrf/WRFUserARW.ncl"    ; loaded from NCL V6.4.0 onward.
                                                              ; No need for user to explicitly load.

	function wrf_user_unstagger (
		varin      : numeric,  
		unstagDim  : string    
	)

	return_val  :  float or double

Arguments

varin

Variable that needs to be unstaggered. Must be at least a 2 dimensional variable with the rightmost dimensions ny x nx, or a 3 dimensional variable with rightmost dimensions nz x ny x nz to unstagger along the "Z" dimension.

unstagDim

Along which dimension must the variable be unstaggered. Options are "X", "Y" or "Z".

Description

Note: There's a bug in NCL version 5.1.0 of the "WRFUserARW.ncl" file that causes this function to not work with output files from metgrid, if you are trying to access the diagnostics "ua" and "va". If you need a fix, the best thing to do is download a newer version of NCL, since V5.1.0 is a few years old. Otherwise, you can download a fixed version of WRFUserARW.ncl and load this file instead of "$NCARG_ROOT/lib/ncarg/nclscripts/wrf/WRFUserARW.ncl".

A variable unstaggered along the unstagDim. The return dimension will be one less in the unstaggered dimension.

wrf_user_unstagger is part of a library of functions and procedures in WRFUserARW.ncl written to help users plot ARW WRF model data.

Questions on this function should be sent to wrfhelp@ucar.edu.

See Also

See the full list of WRF functions.

Examples

Example 1

  load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
  load "$NCARG_ROOT/lib/ncarg/nclscripts/wrf/WRFUserARW.ncl"

  a = addfile("wrfout_d01_2000-01-24_12:00:00.nc","r")


  U = a->U
  ua = wrf_user_unstagger(U,U@stagger)

You can see some other example scripts and their resultant images at:
http://www.mmm.ucar.edu/wrf/OnLineTutorial/Graphics/NCL/