ARTS built-in documentation server

Workspace Method refr_index_airMicrowavesEarth


Microwave refractive index in Earth's atmosphere.

This method just considers pressure, temperature and water
vapour, which should suffice for Earth. For a more general
method, see refr_index_airMicrowavesGeneral.

The refractivity of dry air and water vapour 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

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

The standard expression for Earth and microwaves is used:
   N = k1*(P-e)/T + k2*e/T + k3*e/T^2
where N is refractivity, P is pressure, T is temperature and
e is water vapour partial pressure. The values of k1, k2 and k3
can be modified.

Many different values of k1, k2 and k3 can be found in the
literature. The default values applied here are taken from
Bevis et al., GPS meteorology: Mapping ..., JAM, 1994.
More specifically, these value are found in Table 1, listed
as "Present study". Note that in ARTS Pa is used for pressure
and k1, k2 and k3 must be adjusted accordingly.

Authors: Patrick Eriksson


refr_index_airMicrowavesEarth( refr_index_air, refr_index_air_group, rtp_pressure, rtp_temperature, rtp_vmr, abs_species, k1, k2, k3 )


OUT+INrefr_index_air(Numeric)Real part of the refractive index of air.
OUT+INrefr_index_air_group(Numeric)Group index of refractivity.
INrtp_pressure(Numeric)Pressure at a radiative transfer point.
INrtp_temperature(Numeric)Temperature at a radiative transfer point.
INrtp_vmr(Vector)Absorption species abundances for radiative transfer calculations.
INabs_species(ArrayOfArrayOfSpeciesTag)Tag groups for gas absorption.
GINk1(Numeric, Default: 77.6e-8)Coefficient a, see above
GINk2(Numeric, Default: 70.4e-8)Coefficient b, see above
GINk3(Numeric, Default: 3.739e-3)Coefficient c, see above