VARIABLE : lines
DATA TYPE: ArrayOfLineRecord
DESCRIPTION:
A list of spectral line data.

VARIABLE : lines_per_tg
DATA TYPE: ArrayOfArrayOfLineRecord
DESCRIPTION:
A list of spectral line data for each tag.
Dimensions: (tag_groups.nelem()) (# of lines for this tag)

VARIABLE : tgs
DATA TYPE: TagGroups
DESCRIPTION:
This is an array of arrays of OneTag tag definitions.
It defines the available tag groups for the calculation
of absorption coefficients and weighting functions.
Contrary to the original Bredbeck definition, tags within a
group must belong to the same species, because one VMR profile
is associated with each tag group.

VARIABLE : wfs_tgs
DATA TYPE: TagGroups
DESCRIPTION:
This is an array of arrays of tag group definitions.
It defines the tag groups for the calculation of weighting
functions. The selected tag groups must be a subgroup of the
tag groups defined for the absorption coefficient calculation.

VARIABLE : lineshape
DATA TYPE: ArrayOfLineshapeSpec
DESCRIPTION:
Lineshape specification: function, norm, cutoff. There is one entry for
each abs_tag, not for each species. This means if you have several
abs_tags for different isotopes or transitions of a species, you
may use different lineshapes.

VARIABLE : cont_description_names
DATA TYPE: ArrayOfString
DESCRIPTION:
Continuum model names. This variable should contain a list of
names of continuum models. Associated with this WSV is the WSV
`cont_description_parameters' which should contain continuum
parameters for each model. Allowed models currently are:

H2O-ContStandardSelf: Self component of a simple empirical
   continuum model a la Liebe/Rosenkranz. Needs two parameters.
H2O-ContStandardForeign: Foreign component of a simple empirical
   continuum model a la Liebe/Rosenkranz. Needs two parameters.

VARIABLE : cont_description_parameters
DATA TYPE: ArrayOfVector
DESCRIPTION:
Continuum model parameters. See the WSV `cont_description_names'
for a detailed description of the allowed continuum models. There
should be one parameter vector here for each entry in
`cont_description_names'.

VARIABLE : raw_ptz
DATA TYPE: Matrix
DESCRIPTION:
Matrix has rows:
1. Pressure in Pa
2. Temperature in K
3. Altitude in m

VARIABLE : raw_vmrs
DATA TYPE: ArrayOfMatrix
DESCRIPTION:
The individual VMR profiles. Each species VMR profile comes with a
pressure profile. The different species can hence be on different
grids.
The matrix has rows:
1. Pressure in Pa
2. VMR profile (absolute number)
The array dimension is determined by the number of tag groups.

VARIABLE : p_abs
DATA TYPE: Vector
DESCRIPTION:
The pressure grid for the absorption coefficients [Pa]. This
is the basic independent grid for the absorption calculation, both
in the 1D and 2D case. Therefore it remains a vector, even in 2D.
The "raw" atmospheric data shall be interpolated to p_abs before
the absorption calculations starts.

VARIABLE : f_mono
DATA TYPE: Vector
DESCRIPTION:
The monochromatic frequency grid [Hz]. 

VARIABLE : t_abs
DATA TYPE: Vector
DESCRIPTION:
Temperature associated with the pressures in p_abs [K]

VARIABLE : z_abs
DATA TYPE: Vector
DESCRIPTION:
Vertical altitudes associated with the pressures in p_abs [m]

VARIABLE : h2o_abs
DATA TYPE: Vector
DESCRIPTION:
The total water profile associated with the pressures in p_abs [-]

VARIABLE : n2_abs
DATA TYPE: Vector
DESCRIPTION:
The total nitrogen profile associated with the pressures in p_abs [-]

VARIABLE : vmrs
DATA TYPE: Matrix
DESCRIPTION:
The VMRs (unit: absolute number) on the p_abs grid.
Dimensions: [tag_groups.nelem(), p_abs.nelem()]

VARIABLE : abs
DATA TYPE: Matrix
DESCRIPTION:
The matrix of absorption coefficients (in units of [1/m]).
Dimensions: [f_mono.nelem(), p_abs.nelem()]

VARIABLE : abs_per_tg
DATA TYPE: ArrayOfMatrix
DESCRIPTION:
These are the absorption coefficients individually for each
tag group. The Array contains one matrix for each tag group,
the matrix format is the same as that of abs

VARIABLE : xsec_per_tg
DATA TYPE: ArrayOfMatrix
DESCRIPTION:
These are the cross sections individually for each tag
group. The Array contains one matrix for each tag group,
the matrix format is the same as that of abs

VARIABLE : hse
DATA TYPE: Vector
DESCRIPTION:
This vector holds the parameters for calculating hydrostatic 
equilibrium (HSE). The length of the vector is either 1 or 5, where
the values are: 
   1: On/off flag. 0 = ignore HSE, 1 = consider HSE.
   2: The pressure of the reference point [Pa]. 
   3: The altitude of the reference point [m]. 
   4: Gravitational acceleration at the geoid surface [m/s2]. 
   5: Number of iterations of the calculations.
If the on/off flag is set to 1, the length of the vector must be 5,
while if the flag is 0 a length of 1 is OK.

VARIABLE : emission
DATA TYPE: Index
DESCRIPTION:
Boolean to include emssion in the calculation of spectra.
If this variable is set to 0 (zero) pure transmission calculations 
will be simulated and, for example, yCalc will give optical 
thicknesses instead of radiation intensities.

VARIABLE : za_pencil
DATA TYPE: Vector
DESCRIPTION:
Pencil beam zenith angle grid [deg]. 
The observation direction is specified by the angle between zenith 
and the LOS.

VARIABLE : z_tan
DATA TYPE: Vector
DESCRIPTION:
Tangent altitude for each spectrum [m].
These tangent altitudes include the effect of refraction (if set). 
In the case of a ground intersection, a geometrical prolongation 
below the ground is applied to determine the tangent altitude. 
For upward observations where there are no tangent altitudes, 
*z_tan* is set to 999 km. 
It should be noted that the LOS calculations take *za_pencil* as 
input, not *z_tan*. However, *za_pencil* can be calculated from 
*z_tan* by the function *zaFromZtan*. 

VARIABLE : z_plat
DATA TYPE: Numeric
DESCRIPTION:
Vertical altitude, above the geiod, of the observation platform [m].

VARIABLE : l_step
DATA TYPE: Numeric
DESCRIPTION:
The maximum length, along the LOS, between the points of LOS [m].
The final step length will in most cases equal the selected length.
There are two rare exceptions:
  1. Downward observations from within the atmosphere, where the step
     length is adjusted downwards to get an integer number of steps
     between the sensor and the tangent or ground point.
  2. Limb sounding and the distance from the tangent point to the
     atmospheric limit (the highest absorption altitude) is smaller
     the selected length. The length is then adjusted to this
     distance

VARIABLE : refr
DATA TYPE: Index
DESCRIPTION:
Boolean for inclusion of refraction (0=no refraction, 1=refraction).

VARIABLE : refr_lfac
DATA TYPE: Index
DESCRIPTION:
This factor determines the step length used during the ray tracing 
performed when considering refraction. 
The step length applied is *l_step* divided by *refr_lfac*. 
Accordingly, this factor gives how many ray tracing steps that are 
performed for each step of the LOS.

VARIABLE : refr_model
DATA TYPE: String
DESCRIPTION:
A string giving what parameterization to use for the calculation of 
refractive index. See *refrCalc* for existing choices.

VARIABLE : refr_index
DATA TYPE: Vector
DESCRIPTION:
The refractive index at the pressure levels in p_abs [-].


VARIABLE : r_geoid
DATA TYPE: Numeric
DESCRIPTION:
The local curvature radius of the geoid along the LOS [m].

VARIABLE : z_ground
DATA TYPE: Numeric
DESCRIPTION:
The vertical altitude above the geiod of the ground [m].

VARIABLE : t_ground
DATA TYPE: Numeric
DESCRIPTION:
The physical temperature of the ground [K].

VARIABLE : e_ground
DATA TYPE: Vector
DESCRIPTION:
The ground emission factor for the frequencies in f_mono [0-1].

VARIABLE : los
DATA TYPE: Los
DESCRIPTION:
Structure to define the line of sight (LOS). See los.h for 
definition of the structure.

VARIABLE : source
DATA TYPE: ArrayOfMatrix
DESCRIPTION:
Mean source function between the points of the LOS.

VARIABLE : trans
DATA TYPE: ArrayOfMatrix
DESCRIPTION:
The transmissions between the points of the LOS [-].

VARIABLE : y_space
DATA TYPE: Vector
DESCRIPTION:
Radiation entering the atmosphere at the top of the atmosphere, 
typically cosmic background radiation. This variable is most easily 
set by the function *y_spaceStd*.

VARIABLE : y
DATA TYPE: Vector
DESCRIPTION:
The working set of spectra. 
The spectra from the different zenith angles are appended to form *y*.

VARIABLE : y0
DATA TYPE: Vector
DESCRIPTION:
A reference spectrum. This variable can be used e.g. to save a copy
of *y* or to compare the spectra before and after some operation(s).

VARIABLE : absloswfs
DATA TYPE: ArrayOfMatrix
DESCRIPTION:
Line of sight weighting functions. 
See AUG for definition of this quantity. 

VARIABLE : k_grid
DATA TYPE: Vector
DESCRIPTION:
Retrieval grid to be used in calculation of weighting functions (WFs)
For example, *k_grid* is the pressure altitude grid for species WFs. 
Not all WFs need 'k_grid* as input.

VARIABLE : k
DATA TYPE: Matrix
DESCRIPTION:
The weighting functions (WFs) for a single retrieval/error group.

VARIABLE : k_names
DATA TYPE: ArrayOfString
DESCRIPTION:
Names of the retrieval identies in *k*.

VARIABLE : k_aux
DATA TYPE: Matrix
DESCRIPTION:
Auxiliary data for *k*. The number of rows of this matrix equals the
length of the state vector for the retrieval group (the number of
columns of k).
The columns hold different quantities:
  Col 1: retrieval grid (or correspondingly)
  Col 2: a priori values

VARIABLE : kx
DATA TYPE: Matrix
DESCRIPTION:
The state weighting function matrix.

VARIABLE : kx_names
DATA TYPE: ArrayOfString
DESCRIPTION:
Names of the retrieval identities in *kx*.

VARIABLE : kx_lengths
DATA TYPE: ArrayOfIndex
DESCRIPTION:
The length of the state vector for each retrieval identity in *kx*.

VARIABLE : kx_aux
DATA TYPE: Matrix
DESCRIPTION:
Auxiliary data for *kx*. As *k_aux* but with the data of the 
different retrieval groups appended vertically.

VARIABLE : kb
DATA TYPE: Matrix
DESCRIPTION:
The model parameters weighting function matrix.

VARIABLE : kb_names
DATA TYPE: ArrayOfString
DESCRIPTION:
Names of the model parameter identities in *kb*.

VARIABLE : kb_lengths
DATA TYPE: ArrayOfIndex
DESCRIPTION:
The length of the model vector for each retrieval identity in *kb*.

VARIABLE : kb_aux
DATA TYPE: Matrix
DESCRIPTION:
Auxiliary data for *kb*. As *k_aux* but with the data of the 
different forward model groups appended vertically.

VARIABLE : batchname
DATA TYPE: String
DESCRIPTION:
Default basename for batch data.

VARIABLE : ybatch
DATA TYPE: Matrix
DESCRIPTION:
A batch of spectra.
The spectra are stored as columns in a matrix