The file containing an instrument radiance iamge in watts, (for TIMS it
is six bands of a calibrated image, using the IRAD mode and WATTS units).
Output data set in 16-bit integer format of all the bands of ground
calibrated data. The exact type of data output (e.g. temperature,
radiance, etc) is determined by the MODE parameter.
Output file produced by lowtran, if the default value of DUMMY is used,
no output file will be produced. Also, even if Lowtran is run more than
once by TCAL2, only the last run of Lowtran will have this output file.
Output file produced by lowtran containing a table of radiance and
transmittance versus wavelength, if the default value of DUMMY is used,
no output file will be produced. Also, even if Lowtran is run more than
once by TCAL2, only the last run of Lowtran will have this output file.
Optional input DEM file, which needs to have the same nl and same ns as
the input file, also this file should be 16-bit integer and should be
meters above MSL. TCAL2 finds the minimum and maximum elevation from
this file, then runs Lowtran in that range at an interval specified by
ELEVSTEP. (Lowtran is run twice at each calculated elevation; once at
the maximum deflection of the field of view from nadir and once at the
minimum deflection. For samples between these two deflections,
interpolated values are calculated). When the output temperature or
radiance is being calculated, the elevation of each pixel is looked up
in the DEM and returned values from the run of Lowtran closest in
elevation are used. No interpolation is currently done between
the values Lowtran returns for different elevations.
Input Radiosonde atmospere file. It should be in the following format:
atmtitle = test atmosphere
startatm
altitude pressure temp h2o
(km) (mb) (k) (rh)
3.000 715.009 283.70 48.25
4.000 633.005 277.00 34.91
5.000 559.002 270.30 37.71
6.000 492.000 263.60 34.79
where the number of altitude layers may not exceed 34, pressure can never
be exactly zero, and the lowest altitude must equal the ground altitude.
The altitude must be given in Kilometers.
The possible values for The possible values for
column headers are: the units definitions are:
ALTITUDE PPMV Volume mixing ratio
PRESSURE CM-3 Number density
TEMP GM/KG Mass mixing ratio
H2O GM/M3 Mass density
CO2 MB Partial pressure
O3 DP-K Dew point temp, degrees K (H2O only)
N2O DP-C Dew point temp, degress C (H2O only)
CO RH Relative Humidity (H2O only)
CH4 MB
O2 ATM
NO TORR
SO2 K degrees K (for TEMP)
NO2 C degrees C (for TEMP)
NH3
HNO3
Input filter function file for non-TIMS data. It should be in the
following format:
filtertitle = test filter for TCAL2
startfilter
number of bands = 3
band 1
8.000 0.0264
8.032 0.0268
8.064 0.0275
band 2
8.480 0.0394
8.512 0.0503
band 3
8.800 0.0288
8.832 0.9294
8.864 0.0298
The string following "filtertitle = " is put in a vicar label called
FILTER on the output file.
The strings "startfilter" and "number of bands = 3" are required to tell
the program where to start reading the filter data, these two strings
should be on separate lines. There can be anything in the file before
the "startfilter" line, but after it you may confuse the program if
there are any extra lines starting with the word "band" or if the are
extra lines staring with numbers.
"band 1", "band 2" and "band 3" tell the program where data for each band
begins. The first column of data is the wavelength in microns and the
second column is the response.
Tcal2 finds the minimum and maximum wavelength from all the filters it
reads, and runs Lowtran with the corresponding range of wavenumbers.
(Lowtran parameters V1 and V2, right now the Lowtran parameter DV is
hardcoded to be 5 cm-1). If you have a series of filters covering a wide
wavelength range, Lowtran will take longer to run than if you cover a
narrow range. Specifying FILTLIST keyword will make the program print
to the screen the filter values it has read in from the file and the
filters it has interpolated from these to match Lowtran's output. The
filters for each band in the filter file do not have to have the same
wavelength spacing, a different spline is calculated for each band.
The standard VICAR2 output size field. Default will calibrate
the entire data set.
Example: SIZE = (1,1,200,638)
Starting line (same as SIZE(1)).
Starting sample (same as SIZE(2)).
Number of lines (same as SIZE(3)).
Number of samples (same as SIZE(4)).
This keyword selects the type of decalibration to be performed.
There is a choice of three possibilities:
GRAD - (Ground RADiance)
Radiance values of the ground target in the
scene, incorporating atmospheric corrections.
GTEM - (Ground TEMperature)
Kinetic temperature of the ground target, assuming the
emissivity values given by the parameter "E"
BTEM - (Brightness TEMperature)
Brightness temperature of the ground target.
EMIS - (EMISsivity)
The emissivity of the ground, calculated with
respect to the REFCHAN given (with atmospheric
corrections).
Example: MODE = GRAD
This selects the model atmosphere for which the atmospheric cor-
rections will be computed. The program uses a version of LOWTRAN
as a subroutine, to which AMODEL is passed. The exact parameters
of each model is given in the LOWTRAN handbook. The options in
brief:
TR - TRopical model atmosphere
MS - Midlatitude Summer
MW - Midlatitude Winter
SS - Subarctic Summer
SW - Subarctic Winter
ST - U.S. STandard
RS - User supplied (e.g. Radiosonde) model atmosphere
These same abbreviations are used with the HUMID parameter, with
the same meanings.
Example: LMODEL = SW
The MODELs parameter is used to modify the AMODEL given, or to
specify default atmospheres to use with a RS AMODEL. The choices
are the same as those given in the AMODEL description and with the same
meanings. The seven elements of MODELS specify Lowtran Parameters
M1-M^ and MDEF respectively.
TR - TRopical model atmosphere
MS - Midlatitude Summer
MW - Midlatitude Winter
SS - Subarctic Summer
SW - Subarctic Winter
ST - U.S. STandard
Example: MODELS = (SW,SW,SW,MW,MW,MW,ST)
Used to specify the lowtram parameters H2OFAC, CO2FAC, O3FAC, O2FAC,
CH4FAC and SO2FAC
Variable HEIGHT gives the altitude above mean sea level of the TIMS aircraft as it scanned the particular flight line. The units of HEIGHT are kilometers. A default value of 10 kilometers is used as a nominal approximation of a typical TIMS overflight. Example: HEIGHT = 12.5
The DATUM is the mean elevation in kilometers of the target above mean sea level. A default value of 1 meter is used if the user does not specify the DATUM explicitly. Again, this variable is used only in the MODE = GRAD, GTEM or EMIS cases. Example: DATUM = 0.2
GNDALT is used to specify the ground elevation beneath the
target, if no value is specified, TCAL2 calculates it to be
0.0001 km below DATUM or the values it gets from the DEM.
The temperature of the ground, Lowtrans defaults it to the temperature
of the lowest atmospheric level if nothing is specified
Elevation step between successive runs of Lowtran when using a DEM.
TCAL2 finds the minimum and maximum elevation from the DEM then runs
Lowtran twice at each elevation(i) < max elevation, where
elevation(i) = min elevation + i x elevstep.
So Lowtran must be run
2 x (max elevation - min elevation) / elevstep
times. If elevstep is small enough and the input image is large
enough, TCAL2 may fail because of memory limitations. TCAL2 needs
to run at least
5 x ((max elev - min elev) / elevstep) x bands x samples x 4
bytes.
Pointing of the instrument's center of field of view off
nadir (+ direction is towards the zero sample).
Half the field of view of the instrument, the default: 38.28 is for TIMS
This is the emissivity assumed for each band, when computing the
sky radiance reflected by the ground. In the GTEM mode, these values
are also used to compute the ground kinetic temperature. In the
EMIS mode, the REFCHAN band value is used to set that band's
emissivity.
The band to which the other bands are to be referenced, in the case of Emissivity data, is input through this parameter. The default is band six is used. Example: REFCHAN = 5
TCAL2 uses the date of data acquisition to determine the proper
calibration coefficients. If defaulted, the date in the VICAR
label is used. This parameter is needed if the VICAR label
is incorrect, or if an abnormal calibration set is to be used.
Date is also needed if IEMSCT = 2; in that case TCAL2 calculates DOY
from it for the Lowtran7 parameter IDAY.
The parameters SUNANGLE, OBS_LOC, SUN_LOC, TIME and PSIPO are used when IEMSCT = 2, to specify the position of the sun. There are three allowable combinations to specify: 1) OBS_LOC, SUN_LOC and PSIPO 2) OBS_LOC, TIME and PSIPO 3) SUNANGLE pages 38-39 of the Lowtran manual have (slightly) more information
The parameters SUNANGLE, OBS_LOC, SUN_LOC, TIME and PSIPO are used when IEMSCT = 2, to specify the position of the sun. There are three allowable combinations to specify: 1) OBS_LOC, SUN_LOC and PSIPO 2) OBS_LOC, TIME and PSIPO 3) SUNANGLE pages 38-39 of the Lowtran manual have (slightly) more information
The parameters SUNANGLE, OBS_LOC, SUN_LOC, TIME and PSIPO are used when IEMSCT = 2, to specify the position of the sun. There are three allowable combinations to specify: 1) OBS_LOC, SUN_LOC and PSIPO 2) OBS_LOC, TIME and PSIPO 3) SUNANGLE pages 38-39 of the Lowtran manual have (slightly) more information
The parameters SUNANGLE, OBS_LOC, SUN_LOC, TIME and PSIPO are used when IEMSCT = 2, to specify the position of the sun. There are three allowable combinations to specify: 1) OBS_LOC, SUN_LOC and PSIPO 2) OBS_LOC, TIME and PSIPO 3) SUNANGLE pages 38-39 of the Lowtran manual have (slightly) more information
The parameters SUNANGLE, OBS_LOC, SUN_LOC, TIME and PSIPO are used when IEMSCT = 2, to specify the position of the sun. There are three allowable combinations to specify: 1) OBS_LOC, SUN_LOC and PSIPO 2) OBS_LOC, TIME and PSIPO 3) SUNANGLE pages 38-39 of the Lowtran manual have (slightly) more information
Asymmetry parameter for use with Henyey-Greenstein Phase function. This parameter can be used only if IEMSCT = 2. If it is not specified, then Lowtran7's MIE-generated database of aerosol phase functions will be used instead.
Controls what information is printed to the terminal, the choices are:
low7inp - print out some Lowtran input information
filtlist - print out the instrument filter functions and the
interpolated function calculated by TCAL2
atmlist - print some atmosphere model stuff
demlist - for each band, print out the radiation up,
transmission and radiation down at each elevation
are the zeroes in the DEM data? Use 'DATA' to indicate the zeroes in the DEM should be considered data points with 0 meter elevation. Use 'NODATA' to indicate the zeroes in the DEM are null data flags, the zeroes will be ignored, and the output images will have zeroes whereever the DEM has zeroes.$ Return