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cz2ccm

Computes geopotential height in hybrid coordinates.

Prototype

	function cz2ccm (
		ps       : numeric,  
		phis     : numeric,  
		tv       : numeric,  
		p0   [1] : numeric,  
		hyam [*] : numeric,  
		hybm [*] : numeric,  
		hyai [*] : numeric,  
		hybi [*] : numeric   
	)

	return_val [dimsizes(tv)] :  numeric

Arguments

ps

A multi-dimensional array equal to the surface pressure in Pa. The rightmost two dimensions must be lat and lon.

phis

A two- or three-dimensional array or scalar value equal to the surface geopotential in m^2/s^2. The two rightmost dimensions must be the same as the the two rightmost dimensions of tv

tv

A multi-dimensional array or scalar value equal to the virtual temperature. The data must be ordered top-to-bottom. The rightmost three dimensions must level, lat, and lon.

p0

A scalar value equal to the hybrid base pressure in Pa. If not available, use 100000.

hyam

A one-dimensional array of hybrid coordinate coefficients for base pressures (layer midpoints) ordered bottom-to-top.

hybm

A one-dimensional array of hybrid coordinate coefficients for surface pressures (layer midpoints) ordered bottom-to-top.

hyai

A one-dimensional array of hybrid A coefficients (layer interfaces) ordered bottom-to-top.

hybi

A one-dimensional array of hybrid B coefficients (layer interfaces) ordered bottom-to-top.

Return value

A multi-dimensional array of the same size as tv. The data will be ordered from top-to-bottom. Double if ps and tv are double, float otherwise.

Description

Computes geopotential height in hybrid coordinates. Missing values are not allowed. This is the exact routine used in the former Cray CESM Processor.

Examples

Example 1

This example reads two files. The first file contains information the second file does not contain. The second file contains daily means of numerous variables for one month (30 time steps). The temperature (T) and specific humidities (Q) are read directly from the file and are used to calculate the virtual temperature. Note that the order of the hybrid coordinates has been temporarily reversed [(::-1)] to match the input requirements.

begin

  diri    = "/fs/scd/home1/shea/ncldata_input/"
  filphis = "01-50.nc"                       ; file with PHIS field
  f       = addfile (diri+filphis+".nc" , "r") 
                                          ; strip off various fields
  phis    = f->PHIS                       ; read PHIS to memory
  lat     = f->lat
  lon     = f->lon
  lev     = f->lev
  ilev    = f->ilev
  hyam    = f->hyam
  hybm    = f->hybm
  hyai    = f->hyai
  hybi    = f->hybi

  fili    = (/ "ha0001.nc" /)
  f       = addfile (diri+fili , "r") ; daily files

  ps    = f->PS                       ; get sfc pres
  tv    = f->T*(1.+0.61*f->Q)         ; calculate virtual temperature
  p0    = f->P0                       ; get constant

                                      ; calculate z2 at all 30 time steps
  z2 = cz2ccm(ps,phis,tv,p0,hyam(::-1),hybm(::-1),hyai(::-1),hybi(::-1))

end 
Example 2

Convert the output from example 1 to pressure levels.

begin

  [snip part one above]

  fili    = (/ "ha0001.nc" /)
  f       = addfile (diri+fili , "r") ; daily files

  ps      = f->PS                     ; get sfc pres
  tv      = f->T*(1.+0.61*f->Q)       ; calculate virtual temperature
  p0      = f->P0                     ; get constant

                                      ; calculate Z2 at all 30 time steps
  Z2 = cz2ccm(ps,phis,tv,p0,hyam(::-1),hybm(::-1),hyai(::-1),hybi(::-1))

  pnew = (/ 850., 500., 200.  /)      ; desired output levels [mb] 
  knew = dimsizes(pnew)
  P0mb = 1000.                        ; reference pressure [mb]
 
  Znew = vinth2p(Z2,hyam,hybm,pnew,ps,1,P0mb,2,True)
 
end