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omega_ccm_driver

Computes vertical pressure velocity [omega] via model diagnostic code.

Prototype

load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"  ; This library is automatically loaded
                                                             ; from NCL V6.2.0 onward.
                                                             ; No need for user to explicitly load.

	function omega_ccm_driver (
		p0   [1] : numeric,  
		psfc     : numeric,  
		u        : numeric,  
		v        : numeric,  
		hyam [*] : numeric,  
		hybm [*] : numeric,  
		hyai [*] : numeric,  
		hybi [*] : numeric   
	)

	return_val [dimsizes(u)] :  float or double

Arguments

A scalar value equal to the surface reference pressure. Must have the same units as psfc.

psfc

An array of 2 or 3 dimensions containing surface pressure [Pa]. The two rightmost dimensions must be lat x lon [e.g. PSFC(time,lat,lon)]. To be consistent with the u and v variables, the grid must be in ascending latitude order.

An array of 3 or 4 dimensions containing zonal wind component. The three rightmost dimensions must be lev x lat x lon [e.g. U(time,lev,lat,lon)]. The variable must be ordered south-to-north because the uv2dvG function is used to calculate divergence. This function uses spherical harmonics and requires the grid to be in ascending latitude order (ie, south-to-north).

An array of 3 or 4 dimensions containing meridional wind component. Same dimension structure as u.

hyam

A one-dimensional array containing the mid-level hybrid A coefficients. Must have the same dimension as the level dimension of u. The order must be top-to-bottom.

hybm

A one-dimensional array containing the mid-level hybrid B coefficients. Must have the same dimension as the level dimension of u. The order must be top-to-bottom.

hyai

A one-dimensional array containing the interface-level hybrid A coefficients. The dimension size is one greater than the dimension size of u. The order must be top-to-bottom.

hybi

A one-dimensional array containing the interface-level hybrid B coefficients. The dimension size is one greater than the dimension size of u. The order must be top-to-bottom.

Return value

A double array is returned if u is double; a float array is returned otherwise. The returned array will be of dimension size dimsizes (u).

Description

This function simplifies the use of omega_ccm by using commonly available variables. It computes assorted intermediate quantities that are input to omega_ccm.

Examples

Example 1

Use the driver located in contributed.ncl. It calculates the intermediate quantities required for omega_ccm.

  load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"


  fccm  = addfile ("dummy_ccm.nc" , "r")
  hyam  = fccm->hyam                   
  hybm  = fccm->hybm
  hyai  = fccm->hyai                   
  hybi  = fccm->hybi
  p0    = fccm->P0
  psfc  = fccm->PS
  u     = fccm->U 
  v     = fccm->V 
  omega = omega_ccm_driver(p0,psfc,u,v,hyam,hybm,hyai,hybi)

Example 2