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wrf_user_intrp3d

Interpolates ARW WRF model data vertically or horizontally.

Available in version 4.3.1 or later.

Prototype

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

	function wrf_user_intrp3d (
		var3d      : numeric,  
		vert       : numeric,  
		plot_type  : string,   
		loc    [*] : numeric,  ; up to four values
		angle      : numeric,  
		res    [1] : logical   
	)

	return_val  :  numeric

Arguments

var3d

Data on model levels that will be interpolated. The rightmost dimensions of this array is nz x ny x nx.

vert

Array of vertical coordinate to interpolate too. This must either be pressure/height. Dimensions must be the same as those of var3d.

plot_type

Plot orientation. Use "h" for horizontal plots, and "v" for vertical cross sections.

loc

Interpolation information. Can contain up to four scalar values.

Use a single value for horizontal plots, eg. 500. for 500hPa or 2000. for 2km.

For cross sections:

Use 2 values if plotting a plane through a given point on the model domain. The two values represent the x/y location through which the plane will pass. Must also specify angle in this case.

Use 4 values if plotting from point A to point B. The 4 values represent the x/y locations of points A and B.

angle

Only valid for cross sections where a plane will be plotted through a given point on the model domain. 0.0 represents a S-N cross section and 90.0 a W-E cross section.

res

Set to True if plotting a cross section from point A to point B; otherwise set to False.

Return value

Data interpolated to a horizontal or vertical plane.

Description

This function interpolates data from model levels to either a horizonal or vertical plane. The script can interpolate to either height or pressure.

wrf_user_intrp3d is part of a library of functions and procedures in WRFUserARW.ncl written to help users plot ARW WRF model data.

WRF-related questions 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")

  wks = gsn_open_wks("x11","test")

  time = 1
  tc = wrf_user_getvar(a,"tc",time)        ; T [C]
  rh = wrf_user_getvar(a,"rh",time)        ; relative humidity
  z  = wrf_user_getvar(a, "z",time)        ; grid point height
  p  = wrf_user_getvar(a, "pressure",time) ; total pressure

  dimsrh = dimsizes(rh)

  plane = (/ dimsrh(2)/2, dimsrh(1)/2, /)    ; pivot point is center of domain

  ; Extract data on a N-S cross section that runs through "plane"
  ; Interpolate to height
  rh_plane1 = wrf_user_intrp3d(rh,z,"v",plane,0.0,False)
  tc_plane1 = wrf_user_intrp3d(tc,z,"v",plane,0.0,False)

  ; Extract data on a W-E cross section that runs through "plane" 
  ; Interpolate to pressure
  rh_plane2 = wrf_user_intrp3d(rh,p,"v",plane,90.0,False)
  tc_plane2 = wrf_user_intrp3d(tc,p,"v",plane,90.0,False)

Example 2

  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")

  time = 1
  tc = wrf_user_getvar(a,"tc",time)   ; T [C]
  z  = wrf_user_getvar(a,"z",time)    ; z on mass points

  plane = (/  40,81 , 259,81  /) ; approx. START x;y and END x;y point

  ; Extract cross section from point A to point B, as defined in "plane"
  ; And vertically interpolate to height coordinates ("z")
  tc_plane = wrf_user_intrp3d(tc,z,"v",plane,0.,True)

Example 3

  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")

  time = 1
  tc = wrf_user_getvar(a,"tc",time)       ; T [C]
  p  = wrf_user_getvar(a,"pressure",time) ; total pressure

  ; Horizontally interpolate to pressure coordinates ("p")
  pressure = 850.   ; 850 hPa
  tc_plane = wrf_user_intrp3d(tc,p,"h",pressure,0.,False)

You can see some other example scripts and their resultant images at:

http://www.mmm.ucar.edu/wrf/OnLineTutorial/Graphics/NCL/