wrf_tk

Calculates temperature in [K] from ARW WRF model output.

Prototype

	function wrf_tk (
		P      : numeric,  
		theta  : numeric   
	)

	return_val [dimsizes(P)] :  float or double

Arguments

An array of full pressure (perturbation + base state pressure). The rightmost three dimensions must be level (bottom_top) x lat (south_north) x lon (west_east). Units are [Pa].

An array of potential temperature (perturbation + reference temperature) or (theta+t0) with the same dimension structure as P. Units are [K].

Return value

A multi-dimensional array of the same size as P containing temperature in [K]. The type will be double if P or T are double, and float otherwise.

Description

This function returns temperature in [K]. The return variable will contain two attributes:

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

See Also

wrf_rh

Examples

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

  ncl_filedump wrfout_d01_2000-01-24_12:00:00.nc

Example 1

Read and process a 4d array. The arguments are variables from WRF data.

Note that if your netCDF file doesn't have a ".nc" suffix, you must include it in the call to addfile so it knows what kind of file to open. The addfile call below will cause NCL to look for both a file called "wrfout_d01_2000-01-24_12:00:00.nc" and "wrfout_d01_2000-01-24_12:00:00".

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

  P  = a->P                     ; perturbation
  Pb = a->PB                    ; base state pressure
  P  = P + Pb                   ; total pressure

  T = a->T                  ; perturbation potential temperature (theta+t0)
  T = T + 300.

  TK = wrf_tk (P, T)

  printVarSummary(TK)

The function wrf_user_getvar, (available in the $NCARG_ROOT/lib/ncarg/nclscripts/wrf/WRFUserARW.ncl script) can also be used to calculate many diagnostics in one step.

  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
  tk = wrf_user_getvar(a,"tk",time)  ; calculate tk