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Workspace Method refr_index_airFreeElectrons

Description

Microwave refractive index due to free electrons.

The refractive index of free electrons is added to refr_index_air.
To obtain the complete value, refr_index_air should be set to 1
before calling this WSM. This applies also to refr_index_air_group.

The expression applied is n=sqrt(1-wp^2/w^2) where wp is the plasma
frequency, and w is the angular frequency (the function returns
n-1, that here is slightly negative). This expressions is found in
many textbooks, e.g. Rybicki and Lightman (1979). The above refers
to refr_index_air. refr_index_air_group is sqrt(1+wp^2/w^2).

The expression is dispersive. The frequency applied is the mean of
first and last element of f_grid is selected. This frequency must
be at least twice the plasma frequency.

An error is issued if free electrons not are part of abs_species
(and there exist a corresponding "vmr"-value). This demand is
removed if *demand_vmr_value* is set to 0, but use this option
with care.

Authors: Patrick Eriksson

Synopsis

refr_index_airFreeElectrons(

refr_index_air, refr_index_air_group, f_grid, abs_species, rtp_vmr, demand_vmr_value )

Variables

OUT+IN	refr_index_air	(Numeric)	Real part of the refractive index of air.
OUT+IN	refr_index_air_group	(Numeric)	Group index of refractivity.
IN	f_grid	(Vector)	The frequency grid for monochromatic pencil beam calculations.
IN	abs_species	(ArrayOfArrayOfSpeciesTag)	Tag groups for gas absorption.
IN	rtp_vmr	(Vector)	Absorption species abundances for radiative transfer calculations.
GIN	demand_vmr_value	(Index, Default: 1)	Flag to control if it is demanded that free electrons are in abs_species. Default is that this is demanded.