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Workspace Method iyEmissionStandard

Description

Standard method for radiative transfer calculations with emission.

Designed to be part of iy_main_agenda. That is, only valid
outside the cloudbox (no scattering). Assumes local thermodynamic
equilibrium for emission. The basic calculation strategy is to take
the average of the absorption and the emission source function at
the end points of each step of the propagation path. For details
see the user guide.

The internal radiance unit is determined by your definition of
blackbody radiation inside the atmospheric and surface source
terms. Set iy_unit to "1" if you want this to also be the unit
for output radiances. If you want another output unit, you need to
make sure that the internal unit is [W/m2/Hz/sr] (ie. the frequency
version of the Planck function). The possible choices for iy_unit
are:
 "1"             : No conversion.
 "RJBT"          : Conversion to Rayleigh-Jean brightness
                     temperature.
 "PlanckBT"      : Conversion to Planck brightness temperature.
 "W/(m^2 m sr)"  : Conversion to [W/(m^2 m sr)] (radiance per
                     wavelength unit).
 "W/(m^2 m-1 sr)": Conversion to [W/(m^2 m-1 sr)] (radiance per
                     wavenumber unit).

Please note that there is no way for ARTS to strictly check the
internal unit. In principle, the unit can differ between the
elements. The user must makes sure that any unit conversion is
applied correctly, and in accordance with the calibration of the
instrument of concern. Expressions applied and considerations for
the unit conversion of radiances are discussed in Sec. 5.7 of the
ARTS-2 article.

The following auxiliary data can be obtained:
  "Pressure": The pressure along the propagation path.
     Size: [1,1,1,np].
  "Temperature": The temperature along the propagation path.
     Size: [1,1,1,np].
  "VMR, species X": VMR of the species with index X (zero based).
     For example, adding the string "VMR, species 0" extracts the
     VMR of the first species. Size: [1,1,1,np].
  "Absorption, summed": The total absorption matrix along the
     path. Size: [nf,ns,ns,np].
  "Absorption, species X": The absorption matrix along the path
     for an individual species (X works as for VMR).
     Size: [nf,ns,ns,np].
* "Radiative background": Index value flagging the radiative
     background. The following coding is used: 0=space, 1=surface
     and 2=cloudbox. Size: [nf,1,1,1].
  "iy": The radiance at each point along the path (iy_unit is.
     considered). Size: [nf,ns,1,np].
  "Transmission": The transmission matrix from the surface, space
     or cloudbox, to each propagation path point. The matrix is
     valid for the photon direction. Size: [nf,ns,ns,np].
* "Optical depth": The scalar optical depth between the
     observation point and the end of the primary propagation path
     (ie. the optical depth to the surface or space.). Calculated
     in a pure scalar manner, and not dependent on direction.
     Size: [nf,1,1,1].
where
  nf: Number of frequencies.
  ns: Number of Stokes elements.
  np: Number of propagation path points.

The auxiliary data are returned in iy_aux with quantities
selected by iy_aux_vars. Most variables require that the method
is called directly or by iyCalc. For calculations using yCalc,
the selection is restricted to the variables marked with *.

In addition, these choices are accepted but no calculations are
done:
  "PND, type X": Size: [0,0,0,0].
  "Mass content, X": Size: [0,0,0,0].
See e.g. iyTransmissionStandard for a definition of these
variables. To fill these elements of iy_aux (after calling
this WSM), use iy_auxFillParticleVariables.

Authors: Patrick Eriksson

Synopsis

Variables