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wrf_wetbulb

Calculates wet bulb temperature in K, given pressure in temperature in K and mixing ratio in kg/kg from WRF model output.

Available in version 6.2.0 and later.

Prototype

	function wrf_wetbulb (
		p   : numeric,  
		t   : numeric,  
		qv  : numeric   
	)

	return_val  :  float or double

Arguments

Pressure in [mb]. The rightmost dimensions are bottom_top x south_north x west_east.

Temperature in [K]. An array with the same dimensionality as p.

Water vapor mixing ratio in [kg/kg]. An array with the same dimensionality as p.

Return value

Wet bulb temperature in [K]. The rightmost three dimensions will be bottom_top x south_north x west_east, and the leftmost dimensions, if any, will be the same as p's. The array will contain the same named dimensions as p; otherwise, the rightmost two dimensions will be named "south_north" and "west_east". The type will be double if any of the input is double, and float otherwise.

Description

This function returns wet bulb temperature in K, given pressure in temperature in K and mixing ratio in kg/kg from WRF model output.

You can use wrf_user_getvar with an argument of "tw" to calculate this diagnostic.

The return variable will contain two attributes:

return_val@description = "Wet Bulb Temperature"
return_val@units = "K"

Examples

Note: for WRF variable names and their definitions, you can easily check them by using "ncl_filedump":

  ncl_filedump wrfout_d01_2008-09-29_20:00:00.nc

Example 1

  filename = "wrfout_d01_2008-09-29_20:00:00.nc"
  a = addfile(filename,"r")

  t   = wrf_user_getvar(a,"tk",0)
  p   = wrf_user_getvar(a,"p",0)
  qv  = wrf_user_getvar(a,"QVAPOR",0)
  twb = wrf_wetbulb(p,t,qv)

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