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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 to. This must either be pressure/height. Dimensions must be the same as those of var3d.

If vert is pressure, the units may be either hPa or Pa. If vert is height, then the units of the field must be in m.

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.

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: