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Workspace Method refr_index_airThayer

Description

Microwave refractive index due to gases in the Earth's atmosphere.

The refractivity of dry air and water vapour is added to
refr_index_air. To obtain the complete value, refr_index_air
shoul be set to 1 before calling this WSM. This applies also to
*refr_index_air_group.

The expression used is non-dispersive. Hence, refr_index_air and
refr_index_air_group are identical.

The parameterisation of Thayer (Radio Science, 9, 803-807, 1974)
is used. See also Eq. 3 and 5 of Solheim et al. (JGR, 104,
pp. 9664). The expression can be written as
   N = aP/T + be/T + ce/T^2
where N is refractivity, P is pressure, T is temperature and
e is water vapour partial pressure. The values of a, b and c can
be modified. Default values are taken from Thayer (1974).
Note that Thayer uses mbar for pressures, while in ARTS Pa is used
and a, b and c must be scaled accordingly.

Authors: Patrick Eriksson

Synopsis

refr_index_airThayer(

refr_index_air, refr_index_air_group, rtp_pressure, rtp_temperature, rtp_vmr, abs_species, a, b, c )

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	rtp_pressure	(Numeric)	Pressure at a radiative transfer point.
IN	rtp_temperature	(Numeric)	Temperature at a radiative transfer point.
IN	rtp_vmr	(Vector)	Absorption species abundances for radiative transfer calculations.
IN	abs_species	(ArrayOfArrayOfSpeciesTag)	Tag groups for scalar gas absorption.
GIN	a	(Numeric, Default: 77.6e-8)	Coefficient a, see above
GIN	b	(Numeric, Default: 64.8e-8)	Coefficient b, see above
GIN	c	(Numeric, Default: 3.776e-3)	Coefficient c, see above