======================================================================
=== QPACK ===
======================================================================
===== Status, bug reports, etc. ======================================
Qpack is being implemented by Patrick Eriksson and Carlos Jimenez. The
package is under development and quick changes from the outline below
can be made.
The package is shared following the philosophy of the GNU public
license, this including no warranty what so ever.
Comments, suggestions and bug reports shall be sent to:
patrick@rss.chalmers.se
jimenez@rss.chalmers.se
===== General information ============================================
Qpack is a package of Matlab functions for retrieval work using ARTS
as computational engine. Beside functions for the actual inversion and
setting up the retrieval quantities, the package includes functions to
characterize the retrieval and to optimize the calculation grids.
The input to ARTS is provided in two ways, by control file templates
and a structure with settings, denoted as Q. The final control files
are created by the Qtool in AMI. All input not given by the template
files must be specified by Q. The fields of Q are defined at the end
of this file.
For each retrieval/error quantity there exist a do-field, for example
Q.TEMPERATURE_DO. If the do-field is set to zero, the quantity will be
neglected totally and the other fields of the quantity can be left
undefined. For retrieval/error quantities, the do-field can have a
value between 0 and 3: 0 neglect the quantity totally 1 neglect during
retrieval but calculate error for this quantity 2 treat as observation
error 3 retrieve this quantity However, some quantities, such as
calibration error, cannot be retrieved and the value 3 is not
allowed. Measurement thermal is always turned on.
Fields of Q ending with "_ON" shall be treated as booleans. For
example, Q.CHBIN_ON=0 means that no binning of channels shall be
performed. If a on-field is set to zero, the other fields of the
quantity can be left undefined.
The Q structure shall be defined in a function taking Q as only input
and also returning Q, called a QDF. These functions shall not be
called directly, the Q structure is instead obtained by the function
qpack which calls the specified QDF. The function qpack starts with
setting all do and on variables to zero. In this way it is not
necessary to change all old files with definitions of Q when a new
retrieval/error variable is introduced. The qpack function makes also
some initial manipulations not handled elsewhere, such as setting the
global varaible REPORT_LEVEL used by the out.m in AMI to the value of
Q.QP_LEVEL. See further the help of qpack.
Variables with a low influence of the atmospheric state are
pre-calculated. Quantities such as H, Sx and Se are pre-calculated,
while Kx is not.
Most input files must be in the ARTS ascii format. This is true for
all grids read directly by ARTS. Some files read by Qpack functions
can either by ascii or binary (for example, sensor definitions), but
to be safe, use ascii as this format always works. The file format for
the different quantities is commented below the first corresponding
variable. Please note that the 10-log (decades) is used as altitude
coordinate when defining covariance matrices.
Some quantities are expected to be calculated before doing an
inversion or characterization of the retrieval performance. The
following main quantities shall be pre-calculated: H, Sx and
Se. Together with these main variables, some derived variables are
created for higher flexibility. [!! Describe this !!] The standard
order for the pre-calculations is Sx, H and Se, but it is only
necessary to calculate Sx before H when eigenvector data reduction is
applied. On the other hand, H must always be calculated before Se (to
include a possible data reduction in Se by Hd). The pre-calculated
quantities are stored using the Matlab format (.mat files).
See Qpack strategy section for a bit more of info.
===== Package organization and structure ============================
Qpack is structured into several sub-folders:
=== ./ ===
The only function in the main folder is a function to init the Qpack.
=== Templates/ ===
The control file templates are placed here. The extension of the
templates is ".tmplt".
=== Main/ ===
This folder contains the main functions of Qpack. The main functions
(beside qpack.m) start with "qp_", while so called in-line functions
evoked by the cfile templates starts with "qpi_".
=== CLS/ ===
The functions for doing inversions by constrained least squares, that
is, OEM and Tikhonov regularization. Ordinary least squares is also
handled by these functions for simplicity.
These functions starts with "qpcls_", beside the function doing
the actual inversions that is called just qpcls.m.
=== Setup/ ===
This folder contains various help functions to create and "optimize"
the input files. (I am not sure how much stuff that will be
implemented, but this is at least the general idea.)
The functions in this directory starts with "qpmake_" and
"qpopt_".
=== Samples/ ===
This folder contains a set of sample files to get started with
Qpack. The example case corresponds to the 501.4 GHz band of Odin-SMR,
but please note that the files are only provided as examples and do
not make a perfect basis for simulating the Odin observations.
These files form a full scale, but not extremely large, test case.
In this directory you find a definition of the Q structure matching
the files in the sub-folders. Copy this file (sample_q.m) to your test
directory. Edit the path of the directories to match your environment.
For example, if you want the pre-calculated quantities to be stored in
the folder /home/xxx/Test, you set Q.OUT to this folder.
After this, you should be ready to test Qpack.
===== To include new retrieval and error variables ===================
To include a new retrieval variables the follwong steps are needed:
1. Introduce the needed Q-fields.
2. Modify qp_Sx.
3. Modify qp_kinfo.
4. Modify qpi_Kx or qp_Kx.
5. Modify qpoem:
a. Include variable in map_x.
b. Move retrieved values to X.
6. Check if qpoem_invchar must be modified.
===== The fields of Q ================================================
The Qpack fields are included here for completion, but check also
Qpack/ChangeLog for an understanding of Qpack and possible changes not
reflected here.
1 Report levels
2 Names and directories
3 Atmospheres
4 Tag groups
5 Spectroscopy
6 Hydrostatic equilibrium and RTE
7 Calculation grids
8 Sensor
9 Data Reduction
10 Thermal noise
11 Retrieval/error quantities
12 Conditional simulations
13 OEM retrievals
=== 1 Report levels ===
QP_LEVEL
The report level for the Qpack functions (beside messages directly
from ARTS). The number 0 means no reports, while the numbers 1-3
mean increasing level of verbosity.
The function out.m in AMI is used for printing inside the Qpack functions.
ARTS_LEVEL
ARTS is called with this report level for the screen.
=== 2 Names and directories ===
ARTS
The full path to the ARTS executable to run, e.g.
/u/patrick/arts/src/arts
OUT
Name or full path for storing pre-calculated quantities. For example:
OUT = 'out'
OUT = '/u/patrick/SMR/out'
TMP_AREA
All the calculations are performed in temporary sub-folders to
TMP_AREA. The name of the temporary folders is TmpXXXXXX where
XXXXXX is a random number. The sub-folder is deleted when the
calculations are finished.
SPECTRO_DIR
Full path of the directory for line files and definition of continua.
CALCGRIDS_DIR
Full path of the directory where the calculation grids are stored
(f_mono, za_pencil and p_abs).
SENSOR_DIR
Full path of the directory for sensor files.
RETRIEVDEF_DIR
Full path of the directory for grids and definition of covariance
matrices.
=== 3 Atmospheres ===
APRIORI_VMR
Full path for the a priori VMR profiles. There shall exist a file
for all needed species. This data are only used during the actual
inversion or when generating rand data.
APRIORI_PTZ
Full path for a priori pressure, temperature and altitude file.
The full file name, including extension, shall be given, this in
contrast to APRIORI_VMR where only the main path shall be
specified.
SETUP_VMR
SETUP_PTZ
One or several atmospheres to be used during the pre-calculations.
The format for the VMR profiles and the PTZ files follows the a
priori atmosphere (APRIORI_VMR_DIR and APRIORI_PTZ). Each atmosphere
corresponds to a string in an ARTS string array (see RETRIEVAL_TAGS).
When setting up grids and similar operations, all given atmospheres
are considered to avoid "over-fitting" to a special atmospheric
condition. When only one atmospheric state can be considered, the
first atmosphere is selected. See below for its use with rand data.
==== 4 Tag groups ===
RETRIEVAL_TAGS
The tag groups to be retrieved. The tag groups shall be given as
a Matlab string containing an ARTS string array (also called a
string-string). For example: RETRIEVAL_TAGS = '"O3","ClO"'
OTHER_TAGS
The tag groups beside the retrieval tags. Format as above.
=== 5 Spectroscopy ===
LINEFILE
Name on file defining which transitions to consider for the line-
by-line calculations. The line file should be in the ARTS format.
LINESHAPE
LINESHAPE_FACTOR
LINESHAPE_CUTOFF
Line shape variables. Corresponds to the lineshape workspace variable
(WSV) in ARTS.
CONTINUA
The name of the file defining continua. This file shall look like the
part of an ARTS control file where the continua are described. The
cont_descriptionInit command shall not be part of the file.
=== 6 Hydrostatic equilibrium and RTE ===
HSE_IN_ON
Boolean to ensure that the input atmosphere fulfills hydrostatic
equilibrium. The field is only used when reading the atmosphere
for the first time
HSE_RETRIEVAL_ON
Boolean to tell if hydrostatic equilibrium shall be assumed for the
retrieval. If this field is set to 1, temperature weighting functions
are calculated with hydrostatic eq. and z_abs is recalculated for each
iteration. Note that this field can be important for tropospheric
water retrievals even if the temperature is not retrieved.
HSE_PREF
Pressure of the reference point for hydrostatic equlibrium.
HSE_ZREF
Pressure of the reference point for hydrostatic equlibrium.
PLATFORM_ALTITUDE
Corresponds to the ARTS WSV z_plat.
STEPLENGTH_RTE
Corresponds to the ARTS WSV l_step.
GROUND_ALTITUDE
GROUND_EMISSION
Corresponds to the ARTS WSVs z_ground and e_ground, respectively.
The ground temperature is set to the the first element of t_abs.
REFRACTION_ON
Boolean to turn on refraction.
REFR_METHOD
The method to use for calculation of refractive index. It is
assumed that the method does not need any specific input. For
example: REFR_METHOD = 'Boudouris'
REFR_LFAC
Corresponds to the ARTS WSV with the same name.
EMISSION_ON
Boolean to include emission in the calculations.
=== 7 Calculation grids ===
P_ABS
F_MONO
ZA_PENCIL
The file (with extension) in GRID_DIR defining p_abs, f_mono and
za_pencil, respectively. The files must be in ascii format.
=== 8 Sensor ===
Some information about the sensor calculations is found in the
chapter "Sensor modeling" in AUG.
F_ORDER
ZA_ORDER
These variables define if the spectra shall be treated as piece-
wise linear or cubic when setting up the sensor H-matrix. The
value 1 means piece-wise linear and the value 3 piece-wise cubic.
ANTENNA_ON
Boolean to consider the antenna pattern.
ZA_SENSOR
The zenith angles observed by the sensor (the middle points of
the antenna pattern). This file is only read if an antenna is
considered. If the antenna is neglected, ZA_SENSOR is set to
ZA_PENCIL (in qp_H).
ANTENNA_FILE
The file in SENSOR_DIR defining the antenna pattern. See
hAntennaFromFileAdv for file format.
ANTENNA_ORDER
Determines if the antenna pattern shall be treated to be either
piece-wise linear (1) or cubic (3). See further F_ORDER.
ANTENNA_MOVE
Movement of the antenna (unit is degrees) during the integration.
A constant scanning velocity is assumed.
The value 0 means a fixed antenna during the integration.
DSB_ON
Boolean to consider the image sideband.
DSB_FILE
The file in SENSOR_DIR defining the response of the sideband
filter. See hMixerFromFile for file format.
DSB_ORDER
Determines if the sideband filter response shall be treated to
be either piece-wise linear (1) or cubic (3). See further F_ORDER.
DSB_FPRIMARY
Some frequency of the primary band (to indicate if the upper or
lower band is the primary band).
DSB_LO
The LO frequency.
BACKEND_ON
Boolean to consider the backend (spectrometer).
F_SENSOR
The frequencies recorded by the sensor (the middle points of the
backend channels). This file is only read if a backend is
considered. If both mixer and backend are neglected, F_SENSOR is
set to F_MONO (in qp_H). If backend is neglected but a mixer is
included, F_SENSOR is set to the frequencies in the primary band
(in qp_H).
BACKEND_FILE
The file in SENSOR_DIR defining the backend channel response.
The response of all channels are assumed to be identical.
See hBackendFromFile for file format.
BACKEND_ORDER
Determines if the channel response shall be treated to be either
piece-wise linear (1) or cubic (3). See further F_ORDER.
=== 9 Data reduction ===
BINVIEW_ON
Boolean to turn on binning of subsequent spectra.
BINVIEW_DATA
Corresponds to the input vector bins of hBinView.
BINNING_ON
Boolean to turn on binning of neighboring channels.
BINNING_FILE
Full path of file defining the binning pattern. See hBinFile
for file format.
KRED_ON
Boolean to turn on data reduction by the Kx-matrix version
of the Hotelling transformation. The basic idea is to
do a Hotelling transformation of the spectral space. But as
the spectral variability can be decomposed as:
Sy = KxSxKx' + KbSbKb' + Se
and we are interested in capture the variability of the
parameters to be retrieved (x), the transformation is
calculated only from that variability:
KxSxKx' = E V E'
where E are the eigenvectors and V the eigenvalues.
The Hotteling transformation is derived as:
1. Notice that
KxSxKx' = Kx sqrt(Sx) sqrt(Sx)' Kx' = Kx sqrt(Sx) (Kx sqrt(Sx))'
where sqrt(Sx) is one of the possible square roots of Sx.
2. Then a SVD
Kx sqrt(Sx) = U M V'
where U and V are left and right singular vectors.
3. The eigenvectors are then U as from (1):
E V E' = U M V' (U M V')' = U M M U'
KRED_N
Number of eigenvectors to keep in the data reduction.
KRED_DEPTH
How to do the SVD of Kx sqrt(Sx) during reduction, posibilities:
Different assumptions are implemented for sqrt(Sx):
1.Q.KRED_DEPTH = 0
sqrt(Sx) = I
i.e. Sx is assumed to be the identity matrix
2.Q.KRED_DEPTH = 1
sqrt(Sx) = sqrt(diag(Sx))
i.e. Sx is assumed to be diagonal
3.Q.KRED_DEPTH = 2
sqrt(Sx) = chol(Sx)
i.e. full Sx is used and the sqrt is done by a Choleski
decomposition.
More info in:
Eriksson, P., Jimenez, C., Búhler, S. and Murtagh, D. "A
Hotteling Transformation approach for rapid inversion of
atmospheric spectra", J. Quant Rad. Spectroscopy, pp
2001.
LRED_ON
Boolean to turn on data reduction by the limb version
of the Hotelling transformation. By Limb it means
a special reduction based on combining the reduction based
on Kx with a prior optimization of the spectral input
from a limb observation regarding each specific point of a
retrieval grid. This reduction is useful for a retrieval
method where each element of the retrieved species state
vector is obtained independently, so the spectral input
in the limb observation can be optimized for each element.
So far we use it with the net retrievals from the package
Npack.
The basic idea is to decide which elements for the spectral
input are left for each retrieval point, and then to proceed
with a normal Hotelling transformation of the new spectral
space. In practice is done by doing the Hot transf in a Kx
padded with zeros to leave only the rows (part of the scan)
and columns (the retrieval tag depending on LRED_INDTAGS)
corresponding to each retrieval tag and point.
LRED_HISTEP
This parameter gives the upward distance from the retrieval point
to seletc what upper part of the scan to include in the reduction.
If a tangent altitude corresponding to a zenith angle is there, the
corresponding spectrum is kept.
LRED_LOSTEP
As above but to determine the downward distance.
LRED_INDTAGS
Flag, 1 only the Kx corresponding to the retrieval tag is
left, 0 the whole Kx is used.
LRED_DEPTH
As KRED_DEPTH
LRED_KGRIDS
This gives the retrieval grids where the reduction method
(e.g neural nets) will be doing the retrieval. Notice that
they can be different from SPECIES_KGRIDS in a Q structure
use to generate rnd data (to allow the calculation of Kx
with SPECIES_KGRIDS in a fine grid, independent of the
retrieval grid).
Q.LRED_N
As KRED_N
=== 10 Thermal noise ===
Some information about the thermal noise is found in the
chapter "Measurement errors" in AUG.
MEASNOISE_DO
Treatment of measurement thermal noise (0-2).
MEASNOISE_COVMAT
The file specyfying a covariance matrix to generate
measurement noise. The file data shall have three columns, where the
first column holds frequencies and the second column gives the
standard deviations and the third one gives correlation length (in
frequecny as frequency is the abcisa here. Linear interpolation is
applied to get values for other frequencies (but no extrapolation).
CALINOISE_DO
Treatment of calibration noise (0-2). This noise is correlated
between subsequent viewing angles, in contrast to the measurement
noise.
CALINOISE_COVMAT
As MEASNOISE_FILE but for the calibration noise.
=== 11 Retrieval/error/random quantities ===
SPECIES_KGRIDS
The retrieval grid for each RETRIEVAL_TAGS as a string-string.
For example: SPECIES_KGRIDS = '"grid1.aa","grid2.aa"'
The grids shall be defined in files found in RETRIEVDEF_DIR.
SPECIES_COVMATS
Definition file of Sx for each retrieval tag as a string-string.
The file format of these files are specified in the on-line help
for the ARTS method sFromFile. The altitude coordinate when
specifying the covariance matrices is the 10-log of the pressure,
or decades. A decade is about 16 km. The std is given in relative
units e.g 0.3 means 30% of species apriori concentration.
SPECIES_POSITIVE_ON
Flag to include a positive constraint for the species retrieval
(by retrieving the log of the species profiles). This feature
is only activated for non-linear retrievals.
RECALC_ABS_ON
Flag to force re-calculation of absorption in each iteration of
iterative inversions. Absorption will be automatically be re-
calculated if temperature is retrieved. This flag can be used
when, for example, the self-broadening of water can change
notably between the a priori and true states.
TEMPERATURE_DO
Treatment of temperature (0-3, see the top of the file).
TEMPERATURE_KGRID
The file defining the retrieval/error grid for temperature.
TEMPERATURE_COVMAT
The file defining the temperature covariance matrix. Notice that
the std is given in absolute units e.g. K and not in relative
units as the species.
POINTING_DO
Treatment of pointing off-sets (0-3).
POINTING_PDF
Treatment of pointing offset pdf, 'gaussian' and 'uniform' can be used
to fill this field.
POINTING_STDV
Standard deviation for the pointing off-set if 'gaussian' or
half amplitude of pdf if 'uniform', realizations assumed to be
centered around the nominal zenitth angle.
POINTING_DELTA
Perturbation to apply for calculation of the weighting function.
Unit is degrees.
POINTING_COR
Set to 1, porinting error perfectly correlated, i.e. it's a
pointing offset; set to 0, totally uncorrelated; so far no
more refined schemes set (e.g linear drifts).
CONTABS_DO
Treatment of continuum absorption (0-3). The
CONTABS_ORDER
Polynomial order for the continuum fitting.
CONTABS_LIMITS
A vector of length 2 specifying the frequency limits of the fit.
If this field is empty (but exists), the limits are set to the first
and last value of F_MONO.
CONTABS_KGRID
The file defining the retrieval/error grid for continuum
absorption.
CONTABS_COVMAT
The file defining the continuum absorption covariance matrix.
The standard deviations shall be given in percentages with
respect to the absorption of the species in CONTABS_REF_SPECIES.
The given percentages are converted to absorption values [1/m]
by calculating the absorption of the reference species and
multiplicate the percentages with the absorption at the fitting
points.
CONTABS_REF_SPECIES
Reference species when defining the standard deviations in the
covriance matrix for continuum absorption. See further above
for CONTABS_COVMAT.
EGROUND_DO
Treatment of ground emission (0-3).
EGROUND_LIMITS
A common value for the ground emission is used inside each specified
frequency range. Values outside the range of F_MONO can be given.
The values are given as a vector and gives the starting point of
each range, beside the last value that gives the end point of the
last range. Range 1 ends where range 2 starts etc. The ranges for
EGROUND_LIMITS=[f1 f2 f3 f4] are:
f1 <= f < f2
f2 <= f < f3
f3 <= f <= f4
An example: if the ground emission is assumed to be
different in primary and image bands, but to be constant inside each
band, EGROUND_LIMITS can be set to [0 f_lo 1e99] where f_lo is the
LO frequency.
If parts of F_MONO are outside the specified ranges, no retrieval of
the ground emission will be perfomed for those parts.
If EGROUND_LIMITS is set to be empty, this means that each frequency
shall be treated seperately.
EGROUND_COVMAT
Definition file of Sx/Sb for the ground emission. Standard deviations
and correlation lengths are given as functions of frequency. The mean
of the first and last element of F_MONO inside each range given by
EGROUND_LIMITS is used when interpolating the given values.
POLYFIT_DO
Treatment of polynomial fit to baseline ripple (0-3).
POLYFIT_ORDER
Order of polynomial fit.
POLYFIT_COVMATS
Definition file of Sx/Sb for each polynomial coefficient, given
as a string-string. The number of files shall be POLFIT_ORDER+1.
The standard deviations are given in intensity unit. The
correlation length refers to the zenith angles and the unit is
accordingly degrees.
PPOLYFIT_DO
PPOLYFIT_ORDER
PPOLYFIT_COVMATS
PPOLYFIT_LIMITS
Variables for piecewise polynomial baseline fit. The variables
PPOLYFIT_DO, PPOLYFIT_ORDER and PPOLYFIT_COVMATS act as the
corresponding POLYFIT variables. All the polynomials have the
same order and a priori uncertainty. The variable PPOLYFIT_LIMITS
is a vector with the limits between the different polynomials.
The end limits must be specified and the length of PPOLYFIT_LIMITS
is accordingly the number of polynomials + 1.
=== 12 Conditional simulations ===
NUMBER_DO
If different from 0 a random set following the statistics given
in the _DO variables will be calculated. Those _DO variables
larger than 0 are included in the caluclations. NUMBER_DO
gives the number of rnd realizations for each variable. The
number of spectra created is also NUMBER_DO, i.e for spectrum
i the i realizations for each variable defined a state i
used to generate spectrum i. See below generating random sets.
=== 13 Retrievals ===
Retrievals by optimal estimation (OEM), Tikhonov regularization (TR)
and ordinary (weighted) least squares (WLS) are here handled with the
same functions as far as possible. The name constrained least squares
is used as a common name for the methods (WLS is not a CLS method, but
is included here for simplicity).
NOTE that so far only OEM is working.
RETRIEVAL METHOD
String with the acronym of the retrieval method to use.
Allowed options are:
'oem'
CLS_NONLIN_ON
Boolean to turn on nonlinear retrievals. The Marquardt- Levenberg
scheme is used for the iterations. See qp_oem for more details.
All CLS variables below are only needed for non-linear inversions.
CLS_GA_START_VALUE
Start value for gamma in the Marquardt-Levenberg iteration.
CLS_GA_FAC_WHEN_OK
The factor with which gamma is decreased when an iteration is
succesful.
CLS_GA_FAC_WHEN_NOT_OK
The factor with which gamma is increased when an iteration is not
successful.
CLS_GA_LOWER_THRESHOLD
When gamma equals or is below this value, gamma is set to zero.
CLS_GA_UPPER_LIMIT
When gamma equals or is above this value, the iterations are
stopped.
CLS_STOP
Stop criterion for the iteration. The quantity used to check if
convergence is reached is the change of the state vector from one
iteration to next, scaled with Sx and the length of x. See qp_oem
for details.
CLS_MAX_ITER
An upper limit on the number of iterations to be performed.
===== Qpack strategy ===============================================
1 Doing a measurement characterization
2 Doing an optimal inversion
3 Generating random sets
=== 1 Doing a meassurement characterization ===
The _DO fields from 1-11 are treated as:
- 0 the variable is ignored, i.e. no error is calculated
- 1 calculates error as Dy K S K' Dy' but it's not
treated as observation error, i.e it was not
included in the derivation of Se and Dy
- 2 treats the variable as observation error, i.e
it is included in Se and used in deriving Dy,
and of course the error is calculated as 1.
- 3 the variable will be retrieved, so it's part
of the vector state x and the retrieval error
will be calculated by adding the contribution
from all the variables treated as 1 and 2.
The statistics for the characterization are described by the _COVMATS
and _KGRID fields.
Use qp_invchar or qpcls_invchar.
=== 2 Doing an optimal inversion retrieval ===
The retrieval variables are given by _DO as 3 and the variables treated
as observation errors by _DO as 2. Variables _DO 1 or 0 are ignored
here.
The retrieval grids are given by _KGRID fields, and the statistics to
construct the Sx matrix are taken from _COVMATS.
If given an observation Qc is a structure for characterization and Qo
for OEM inversion, the normal procedure will be Qo = Qc + OEM fields,
but in principle it is possible to have differences, e.g. _COVMATS,
we characterize with the best information but we retrieve by
constraining the solution with different statistics - authors of the
document not very keen on this ,-)
Use qpcls.
=== 3 Generating random sets ====
NUMBER_DO gives the number of realizations, variables with _DO fields > 0
are disturbed around the a priori state with the variability given by
_COVMAT. _KGRID fields are only used in a reduction based on Kx is done,
in which case the retieval grid is needed.
APRIORI_VMR_DIR
APRIORI_PTZ
SETUP_VMR_DIRS
SETUP_PTZ
If no SETUP fields are given the APRIORI fields give the atmosphere where
to take the species profiles to be randomly modified. If SETUP fields are
given the APRIORI fields will be ignored. The idea is to generate sets of
profiles-spectra where the profiles correspond to a more than one mean
state. Thing can get a bit tricky, for instance if as part of the sensor
a reduction based on Kx is done, the APRIORI fields will be used as
a priori atmosphere when generating the Kx, so it might be a good idea if
the APRIORI atmosphere is a mean state from the SETUP atmospheres.
By qp_rnd_atm, qp_rnd_sensor and qp_rnd_atmxsensor.
Files saved [Q.OUT'.ybatch'] with raw spectra, [Q.OUT'.measnoise']
and so on with rand fields from the sensor, and [Q.OUT'.ysensor']
with simulated spectra at the sensor output.